/* ============================================================
   Swift with Mayur — design system
   Playful / illustrated. Light + dark. No external assets.
   ============================================================ */

:root {
  --font-display: "Iowan Old Style", "Charter", "Palatino Linotype", Palatino, Georgia, serif;
  --font-round: ui-rounded, "SF Pro Rounded", "Nunito", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-body: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", sans-serif;
  --font-mono: ui-monospace, "SF Mono", SFMono-Regular, Menlo, Consolas, monospace;

  /* neutral cool greys; cards are white so they lift off the page */
  --bg: #F3F3F1;
  --bg-dot: #E2E2DE;
  --surface: #FFFFFF;
  --surface-2: #F7F7F5;
  --surface-3: #ECECE9;
  --ink: #161618;
  --ink-2: #47474D;
  --muted: #6B6B72;
  --line: #E4E4E1;
  --line-strong: #D3D3CF;

  /* heritage accents: racing green leads, brass is the bright action colour */
  --green: #1E5B43;
  --green-soft: #E3EEE8;
  --brass: #8A5D08;
  --brass-soft: #F6ECD4;
  --brass-bright: #E3B23C;
  --on-brass: #2B1F00;
  --slate: #3F6787;
  --slate-soft: #E3EBF2;
  --leaf: #276F4F;
  --leaf-soft: #E1F1E8;
  --oxblood: #9B3B32;
  --oxblood-soft: #F6E4E1;
  --plum: #8A4A6B;
  --plum-soft: #F3E6EE;

  --radius-lg: 22px;
  --radius: 16px;
  --radius-sm: 12px;
  --shadow-sm: 0 1px 2px rgba(15, 15, 18, .05);
  --shadow: 0 1px 2px rgba(15, 15, 18, .04), 0 12px 28px -18px rgba(15, 15, 18, .2);
  --shadow-lift: 0 2px 6px rgba(15, 15, 18, .05), 0 22px 44px -22px rgba(15, 15, 18, .26);

  --ease-out: cubic-bezier(.2, .8, .2, 1);
  --topbar-h: 66px;
  --sidebar-w: 274px;
}

/* near-black layers, not pure #000, so cards read as surfaces rather than holes */
[data-theme="dark"] {
  --bg: #0A0A0B;
  --bg-dot: #1A1A1D;
  --surface: #141416;
  --surface-2: #1A1A1D;
  --surface-3: #232327;
  --ink: #EDEDEF;
  --ink-2: #B4B4BB;
  --muted: #85858D;
  --line: #242428;
  --line-strong: #33333A;

  --green: #6FC79F;
  --green-soft: #13261E;
  --brass: #F2C14E;
  --brass-soft: #2A2210;
  --brass-bright: #F2C14E;
  --slate: #8FB3D4;
  --slate-soft: #15202B;
  --leaf: #7FD6A8;
  --leaf-soft: #11261B;
  --oxblood: #E58A7D;
  --oxblood-soft: #2E1715;
  --plum: #D59BBE;
  --plum-soft: #2A1823;

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, .4);
  --shadow: 0 1px 2px rgba(0, 0, 0, .4), 0 14px 30px -18px rgba(0, 0, 0, .8);
  --shadow-lift: 0 2px 6px rgba(0, 0, 0, .4), 0 22px 44px -20px rgba(0, 0, 0, .9);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background:
    radial-gradient(circle at 10% -10%, color-mix(in srgb, var(--green) 6%, transparent), transparent 44%),
    radial-gradient(circle at 95% 0%, color-mix(in srgb, var(--brass-bright) 5%, transparent), transparent 40%),
    var(--bg);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.62;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

::selection { background: color-mix(in srgb, var(--green) 26%, transparent); }

a { color: var(--green); text-underline-offset: 2px; }

code, kbd, pre { font-family: var(--font-mono); font-size: .875em; }

code {
  background: var(--surface-2);
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: .1em .38em;
  white-space: nowrap;
  color: var(--ink);
}

pre {
  margin: 0;
  background: var(--surface-2);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 14px 16px;
  overflow-x: auto;
  line-height: 1.55;
  tab-size: 2;
}
pre code { background: none; border: 0; padding: 0; white-space: pre; }

kbd {
  background: var(--surface);
  border: 1px solid var(--line-strong);
  border-bottom-width: 2px;
  border-radius: 6px;
  padding: .05em .4em;
  font-size: .78em;
  color: var(--ink-2);
}

/* ---------------- top bar ---------------- */

.topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  height: var(--topbar-h);
  display: flex;
  align-items: center;
  gap: 18px;
  padding: 0 clamp(14px, 3vw, 30px);
  background: color-mix(in srgb, var(--bg) 86%, transparent);
  backdrop-filter: saturate(140%) blur(14px);
  -webkit-backdrop-filter: saturate(140%) blur(14px);
  border-bottom: 1px solid var(--line);
}

.brand {
  display: flex;
  align-items: center;
  gap: 11px;
  text-decoration: none;
  color: inherit;
  flex-shrink: 0;
}
.brand-mark { display: grid; place-items: center; }
.brand-text { display: flex; flex-direction: column; line-height: 1.1; }
.brand-text strong { font-family: var(--font-display); font-size: 17px; letter-spacing: -.2px; }
.brand-text small { font-size: 11.5px; color: var(--muted); letter-spacing: .2px; }

.modes {
  display: flex;
  gap: 3px;
  padding: 4px;
  margin-left: 8px;
  background: var(--surface-2);
  border: 1px solid var(--line);
  border-radius: 999px;
}
.mode-btn {
  appearance: none;
  border: 0;
  background: transparent;
  color: var(--ink-2);
  font: inherit;
  font-size: 13.5px;
  font-weight: 600;
  padding: 6px 16px;
  border-radius: 999px;
  cursor: pointer;
  transition: background .18s, color .18s, box-shadow .18s;
}
.mode-btn:hover { color: var(--ink); }
.mode-btn.is-on {
  background: var(--surface);
  color: var(--green);
  box-shadow: var(--shadow-sm);
}

.tools { margin-left: auto; display: flex; align-items: center; gap: 9px; }

.search {
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 0 12px;
  height: 38px;
  width: clamp(150px, 26vw, 300px);
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--muted);
  transition: border-color .18s, box-shadow .18s;
}
.search:focus-within {
  border-color: color-mix(in srgb, var(--green) 55%, var(--line));
  box-shadow: 0 0 0 4px color-mix(in srgb, var(--green) 14%, transparent);
}
.search input {
  border: 0;
  outline: 0;
  background: none;
  font: inherit;
  font-size: 13.5px;
  color: var(--ink);
  width: 100%;
}
.search input::placeholder { color: var(--muted); }

.icon-btn {
  height: 38px;
  width: 38px;
  display: grid;
  place-items: center;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--ink-2);
  font-size: 16px;
  cursor: pointer;
  transition: transform .18s, border-color .18s, color .18s;
}
.icon-btn:hover { transform: translateY(-1px); border-color: var(--line-strong); color: var(--ink); }
.menu-btn { display: none; font-size: 15px; }
[data-theme="light"] .theme-moon { display: none; }
[data-theme="dark"] .theme-sun { display: none; }

/* ---------------- progress rail ---------------- */

.progress-rail {
  position: sticky;
  top: var(--topbar-h);
  z-index: 40;
  height: 4px;
  background: var(--surface-2);
}
.progress-fill {
  height: 100%;
  width: 0;
  border-radius: 0 999px 999px 0;
  background: linear-gradient(90deg, var(--leaf), var(--slate), var(--green));
  transition: width .4s cubic-bezier(.2, .9, .3, 1);
}

/* ---------------- layout ---------------- */

.layout {
  display: grid;
  grid-template-columns: var(--sidebar-w) minmax(0, clamp(860px, 66vw, 1180px));
  justify-content: center;
  gap: clamp(18px, 3vw, 46px);
  max-width: none;
  margin: 0;
  padding: 0 clamp(14px, 4.5vw, 96px);
  align-items: start;
}

.sidebar {
  position: sticky;
  top: calc(var(--topbar-h) + 18px);
  max-height: calc(100vh - var(--topbar-h) - 36px);
  overflow-y: auto;
  padding: 22px 0 40px;
  scrollbar-width: thin;
}

.sidebar-title {
  font-family: var(--font-round);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: .09em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 0 0 10px 12px;
}

.nav-list { list-style: none; margin: 0 0 26px; padding: 0; display: grid; gap: 2px; }

.nav-link {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 12px;
  border-radius: 11px;
  color: var(--ink-2);
  text-decoration: none;
  font-size: 13.6px;
  line-height: 1.35;
  transition: background .16s, color .16s;
}
.nav-link:hover { background: var(--surface-2); color: var(--ink); }
.nav-link.is-active {
  background: var(--surface);
  color: var(--ink);
  font-weight: 600;
  box-shadow: var(--shadow-sm);
}
.nav-link .nav-num {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--muted);
  min-width: 26px;
  flex-shrink: 0;
}
.nav-link.is-active .nav-num { color: var(--green); }
.nav-link.is-soon { opacity: .55; }
.nav-link .dot {
  margin-left: auto;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--leaf);
  flex-shrink: 0;
}

.sidebar-progress {
  margin: 4px 12px 22px;
  padding: 13px 14px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
}
.sidebar-progress .sp-row { display: flex; justify-content: space-between; font-size: 12px; color: var(--muted); margin-bottom: 7px; }
.sidebar-progress .sp-row strong { color: var(--ink); font-size: 12.5px; }
.sp-track { height: 6px; border-radius: 999px; background: var(--surface-3); overflow: hidden; }
.sp-fill { height: 100%; width: 0; border-radius: 999px; background: linear-gradient(90deg, var(--leaf), var(--slate)); transition: width .5s; }
.sp-reset {
  appearance: none;
  margin-top: 11px;
  width: 100%;
  padding: 5px 8px;
  font: inherit;
  font-size: 11.5px;
  font-weight: 600;
  color: var(--muted);
  background: transparent;
  border: 1px dashed var(--line-strong);
  border-radius: 8px;
  cursor: pointer;
  transition: color .16s, border-color .16s, background .16s;
}
.sp-reset:hover { color: var(--oxblood); border-color: color-mix(in srgb, var(--oxblood) 45%, var(--line-strong)); background: var(--oxblood-soft); }

/* ---------------- view ---------------- */

.view {
  padding: 34px 0 90px;
  min-width: 0;
  max-width: clamp(860px, 66vw, 1180px);
}
body.no-sidebar .view { max-width: 1480px; }

/* ---------------- hero / topic map ---------------- */

.hero {
  position: relative;
  overflow: hidden;
  padding: clamp(26px, 4vw, 42px);
  border-radius: var(--radius-lg);
  background: linear-gradient(150deg, var(--green-soft), var(--surface) 72%);
  border: 1px solid color-mix(in srgb, var(--green) 16%, var(--line));
  box-shadow: var(--shadow);
  margin-bottom: 30px;
}
.hero::after {
  content: "";
  position: absolute;
  inset: auto -40px -70px auto;
  width: 240px;
  height: 240px;
  border-radius: 50%;
  background: radial-gradient(circle, color-mix(in srgb, var(--brass-bright) 22%, transparent), transparent 68%);
  pointer-events: none;
}
.hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-size: 11.5px;
  font-weight: 700;
  letter-spacing: .09em;
  text-transform: uppercase;
  color: var(--green);
  background: color-mix(in srgb, var(--surface) 72%, transparent);
  border: 1px solid color-mix(in srgb, var(--green) 22%, transparent);
  padding: 5px 12px;
  border-radius: 999px;
  margin-bottom: 16px;
}
.hero h1 {
  font-family: var(--font-display);
  font-size: clamp(30px, 5vw, 46px);
  line-height: 1.06;
  letter-spacing: -.02em;
  margin: 0 0 12px;
  max-width: 26ch;
}
.hero p { margin: 0; color: var(--ink-2); max-width: 56ch; font-size: 15.5px; }
.hero-stats { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 24px; }
.stat {
  background: color-mix(in srgb, var(--surface) 82%, transparent);
  border: 1px solid color-mix(in srgb, var(--green) 14%, transparent);
  border-radius: 14px;
  padding: 10px 16px;
  min-width: 96px;
}
.stat b { display: block; font-family: var(--font-round); font-size: 22px; line-height: 1.1; }
.stat span { font-size: 11.5px; color: var(--muted); }

.topic-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(238px, 1fr));
  gap: 14px;
}
.topic-card {
  display: block;
  text-decoration: none;
  color: inherit;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 18px 18px 16px;
  box-shadow: var(--shadow-sm);
  transition: transform .2s, box-shadow .2s, border-color .2s;
  position: relative;
  overflow: hidden;
}
.topic-card::before {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: 4px;
  background: var(--accent, var(--green));
  opacity: .85;
}
.topic-card:hover { transform: translateY(-3px); box-shadow: var(--shadow-lift); border-color: var(--line-strong); }
.topic-card .tc-num {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--muted);
  letter-spacing: .04em;
}
.topic-card h3 {
  font-family: var(--font-display);
  font-size: 16px;
  line-height: 1.25;
  margin: 5px 0 7px;
  letter-spacing: -.01em;
}
.topic-card p { margin: 0; font-size: 12.8px; color: var(--muted); }
.topic-card.is-soon { opacity: .72; }
.topic-card.is-soon:hover { opacity: 1; }
.badge {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  font-size: 10.5px;
  font-weight: 700;
  letter-spacing: .04em;
  text-transform: uppercase;
  padding: 3px 9px;
  border-radius: 999px;
  background: var(--surface-2);
  color: var(--muted);
  margin-top: 12px;
}
.badge-live { background: var(--leaf-soft); color: var(--leaf); }
.badge-soon { background: var(--surface-2); color: var(--muted); }

/* ---------------- section header ---------------- */

.section-head { margin-bottom: 26px; }
.backlink {
  display: inline-flex;
  min-height: 24px;           /* WCAG 2.5.8 target size */
  align-items: center;
  gap: 6px;
  font-size: 12.5px;
  color: var(--muted);
  text-decoration: none;
  margin-bottom: 14px;
}
.backlink:hover { color: var(--green); }
.section-head h1 {
  font-family: var(--font-display);
  font-size: clamp(26px, 4vw, 38px);
  letter-spacing: -.02em;
  line-height: 1.1;
  margin: 0 0 10px;
}
.section-head .lede { color: var(--ink-2); margin: 0 0 18px; max-width: 64ch; font-size: 15.5px; }

.mental-model {
  display: flex;
  gap: 13px;
  padding: 15px 18px;
  border-radius: var(--radius);
  background: linear-gradient(120deg, var(--green-soft), color-mix(in srgb, var(--slate-soft) 60%, var(--green-soft)));
  border: 1px solid color-mix(in srgb, var(--green) 18%, transparent);
  font-size: 14px;
  color: var(--ink-2);
}
.mental-model .mm-icon { font-size: 19px; line-height: 1.3; flex-shrink: 0; }
.mental-model strong { color: var(--ink); }

/* ---------------- chips / filters ---------------- */

.filters {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 7px;
  margin: 22px 0 20px;
  padding-bottom: 16px;
  border-bottom: 1px dashed var(--line-strong);
}
.filter-label { font-size: 11.5px; text-transform: uppercase; letter-spacing: .08em; color: var(--muted); font-weight: 700; margin-right: 2px; }
.chip {
  appearance: none;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--ink-2);
  font: inherit;
  font-size: 12.5px;
  font-weight: 600;
  padding: 5px 13px;
  border-radius: 999px;
  cursor: pointer;
  transition: all .16s;
}
.chip:hover { border-color: var(--line-strong); color: var(--ink); }
.chip.is-on { background: var(--ink); border-color: var(--ink); color: var(--bg); }
a.chip { text-decoration: none; }
.chip-reset { color: var(--oxblood); border-color: transparent; background: transparent; }

/* level colors */
.lv { font-family: var(--font-mono); font-size: 11px; font-weight: 700; padding: 2px 7px; border-radius: 6px; letter-spacing: .02em; }
.lv-L1 { background: var(--leaf-soft); color: var(--leaf); }
.lv-L2 { background: var(--slate-soft); color: var(--slate); }
.lv-L3 { background: var(--brass-soft); color: var(--brass); }
.lv-L5 { background: var(--oxblood-soft); color: var(--oxblood); }
.lv-L8 { background: var(--green-soft); color: var(--green); }
.lv-L13 { background: var(--plum-soft); color: var(--plum); }

/* ---------------- question card ---------------- */

.qcard {
  position: relative;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: clamp(20px, 2.6vw, 30px);
  margin-bottom: 20px;
  box-shadow: var(--shadow);
  scroll-margin-top: calc(var(--topbar-h) + 20px);
  transition: box-shadow .25s, border-color .25s;
}
.qcard::before {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: 5px;
  border-radius: var(--radius-lg) 0 0 var(--radius-lg);
  background: var(--accent, var(--green));
  opacity: .9;
}
.qcard:hover { box-shadow: var(--shadow-lift); }
.qcard.is-hidden { display: none; }

.qmeta { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; margin-bottom: 12px; }
.qnum {
  font-family: var(--font-round);
  font-weight: 800;
  font-size: 12.5px;
  color: var(--accent, var(--green));
  background: color-mix(in srgb, var(--accent, var(--green)) 12%, transparent);
  padding: 3px 10px;
  border-radius: 8px;
}
.qkind { font-size: 11.5px; color: var(--muted); font-weight: 600; letter-spacing: .02em; }
.qstatus { margin-left: auto; display: flex; gap: 6px; }

.qcard h2,
.qcard h3 {
  font-family: var(--font-display);
  font-size: clamp(18px, 2.3vw, 22px);
  line-height: 1.32;
  letter-spacing: -.012em;
  margin: 0 0 16px;
  font-weight: 700;
}

.analogy {
  display: flex;
  gap: 11px;
  padding: 12px 15px;
  border-radius: 14px;
  background: var(--brass-soft);
  border: 1px dashed color-mix(in srgb, var(--brass) 34%, transparent);
  font-size: 14px;
  color: var(--ink-2);
  margin-bottom: 18px;
}
.analogy .a-icon { flex-shrink: 0; font-size: 16px; }
.analogy strong { color: var(--ink); }

.answer { font-size: 15.2px; color: var(--ink-2); }
.answer p { margin: 0 0 11px; }
.answer p:last-child { margin-bottom: 0; }
.answer strong { color: var(--ink); }
.answer ul { margin: 0 0 12px; padding-left: 20px; }
.answer li { margin-bottom: 5px; }

.qblock { margin-top: 18px; }
.qblock-label {
  display: flex;
  align-items: center;
  gap: 7px;
  font-size: 11px;
  font-weight: 800;
  letter-spacing: .09em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 8px;
}
.trap-list, .follow-list { list-style: none; margin: 0; padding: 0; display: grid; gap: 7px; }
.trap-list li, .follow-list li {
  position: relative;
  padding: 9px 13px 9px 34px;
  border-radius: 11px;
  font-size: 13.8px;
  color: var(--ink-2);
  background: var(--surface-2);
  border: 1px solid var(--line);
}
.trap-list li { background: var(--oxblood-soft); border-color: color-mix(in srgb, var(--oxblood) 18%, transparent); }
.trap-list li::before {
  content: "✕";
  position: absolute;
  left: 12px;
  top: 9px;
  font-size: 11px;
  font-weight: 800;
  color: var(--oxblood);
}
.follow-list li::before {
  content: "↳";
  position: absolute;
  left: 13px;
  top: 8px;
  color: var(--slate);
  font-weight: 700;
}
.follow-list li strong { color: var(--ink); }

.codeblock { position: relative; margin-top: 4px; }
.codeblock .copy {
  position: absolute;
  top: 8px;
  right: 8px;
  font-size: 11px;
  padding: 3px 9px;
  border-radius: 7px;
  border: 1px solid var(--line-strong);
  background: var(--surface);
  color: var(--muted);
  cursor: pointer;
  opacity: 0;
  transition: opacity .15s;
}
.codeblock:hover .copy { opacity: 1; }
.codeblock .copy:hover { color: var(--ink); }

.output {
  display: flex;
  gap: 9px;
  align-items: baseline;
  margin-top: 9px;
  font-size: 13px;
  color: var(--leaf);
  font-family: var(--font-mono);
}
.output::before { content: "▸"; color: var(--muted); }

/* syntax colors */
.tok-kw  { color: var(--green); font-weight: 600; }
.tok-str { color: var(--leaf); }
.tok-num { color: var(--brass); }
.tok-cmt { color: var(--muted); font-style: italic; }
.tok-typ { color: var(--slate); }
.tok-attr{ color: var(--oxblood); }

/* links between questions */
.qlinks { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 18px; padding-top: 14px; border-top: 1px dashed var(--line); }
.qlinks a {
  font-size: 11.5px;
  text-decoration: none;
  color: var(--ink-2);
  background: var(--surface-2);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 3px 11px;
  transition: all .15s;
}
.qlinks a:hover { border-color: var(--green); color: var(--green); background: var(--green-soft); }

/* ---------------- diagram player ---------------- */

.diagram {
  margin: 20px 0 4px;
  border-radius: var(--radius);
  border: 1px solid var(--line);
  background:
    radial-gradient(circle at 1px 1px, var(--bg-dot) 1px, transparent 0) 0 0 / 18px 18px,
    var(--surface-2);
  overflow: hidden;
}
.diagram-head {
  display: flex;
  align-items: center;
  gap: 9px;
  padding: 10px 14px;
  border-bottom: 1px solid var(--line);
  background: color-mix(in srgb, var(--surface) 76%, transparent);
}
.diagram-title { font-size: 12.5px; font-weight: 700; font-family: var(--font-round); letter-spacing: .01em; }
.diagram-step { margin-left: auto; font-family: var(--font-mono); font-size: 11px; color: var(--muted); }
.diagram-stage { padding: 12px 8px 2px; min-height: 190px; display: grid; place-items: center; }
.diagram-stage svg { width: 100%; max-width: 560px; height: auto; display: block; overflow: visible; }
.diagram-cap {
  padding: 0 18px 10px;
  font-size: 13px;
  color: var(--ink-2);
  text-align: center;
  min-height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
}
/* Emphasis inside captions stays the same weight as the rest of the line;
   colour carries the emphasis so the text does not look half-bold. */
.diagram-cap em {
  color: var(--ink);
  font-style: normal;
  font-weight: inherit;
}
.diagram-cap code {
  background: none;
  border: 0;
  padding: 0;
  font-size: .94em;
  font-weight: inherit;
  color: var(--ink);
}
.diagram-foot {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 9px 12px;
  border-top: 1px solid var(--line);
  background: color-mix(in srgb, var(--surface) 76%, transparent);
}
.dots { display: flex; gap: 1px; margin: 0 auto; }
.dots button {
  position: relative;
  width: 24px; height: 24px;
  padding: 0;
  border: 0;
  border-radius: 50%;
  background: transparent;
  cursor: pointer;
}
.dots button::before {
  content: "";
  position: absolute;
  left: 50%; top: 50%;
  transform: translate(-50%, -50%);
  width: 7px; height: 7px;
  border-radius: 50%;
  background: var(--line-strong);
  transition: width .2s, background .2s;
}
.dots button.is-on { width: 34px; }
.dots button.is-on::before { width: 19px; border-radius: 999px; background: var(--accent, var(--green)); }
.dbtn {
  appearance: none;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--ink-2);
  font: inherit;
  font-size: 12px;
  font-weight: 600;
  border-radius: 8px;
  padding: 5px 11px;
  cursor: pointer;
  transition: all .15s;
}
.dbtn:hover:not(:disabled) { border-color: var(--line-strong); color: var(--ink); }
.dbtn:disabled { opacity: .38; cursor: default; }
.dbtn-play { color: var(--green); border-color: color-mix(in srgb, var(--green) 30%, var(--line)); }

/* svg diagram primitives */
.d-node rect, .d-node .d-box { transition: none; }
.d-box { stroke-width: 1.6; }
.d-box-value  { fill: var(--green-soft); stroke: var(--green); }
.d-box-ref    { fill: var(--slate-soft);    stroke: var(--slate); }
.d-box-heap   { fill: var(--brass-soft);  stroke: var(--brass); }
.d-box-stack  { fill: var(--plum-soft);   stroke: var(--plum); }
.d-box-nil    { fill: none;               stroke: var(--muted); stroke-dasharray: 5 4; }
.d-box-plain  { fill: var(--surface);     stroke: var(--line-strong); }
.d-box-hot    { fill: color-mix(in srgb, var(--oxblood) 16%, var(--surface)); stroke: var(--oxblood); }
.d-box-ok     { fill: color-mix(in srgb, var(--leaf) 14%, var(--surface)); stroke: var(--leaf); }
.d-box-dim    { opacity: .38; }

.d-t { font-family: var(--font-body); font-size: 12.5px; fill: var(--ink); }
.d-t-mono { font-family: var(--font-mono); font-size: 11.5px; fill: var(--ink); }
.d-t-sm { font-family: var(--font-body); font-size: 10.5px; fill: var(--muted); }
.d-t-b { font-family: var(--font-round); font-size: 12.5px; font-weight: 700; fill: var(--ink); }
.d-t-w { font-family: var(--font-body); font-size: 10px; fill: var(--muted); }

.d-arrow { stroke: var(--ink-2); stroke-width: 1.7; fill: none; }
.d-arrow-dim { opacity: .35; }
.d-arrow-hot { stroke: var(--oxblood); }
.d-arrow-ok { stroke: var(--leaf); }

.anim-pop { animation: d-pop .42s cubic-bezier(.2, 1.2, .4, 1) both; }
@keyframes d-pop {
  from { opacity: 0; transform: translateY(7px) scale(.965); }
  to   { opacity: 1; transform: none; }
}
.anim-draw { stroke-dasharray: 220; stroke-dashoffset: 220; animation: d-draw .55s ease forwards; }
@keyframes d-draw { to { stroke-dashoffset: 0; } }
.anim-fade { animation: d-fade .5s ease both; }
@keyframes d-fade { from { opacity: 0; } to { opacity: 1; } }
.anim-blink { animation: d-blink 1.6s ease-in-out infinite; }
@keyframes d-blink { 0%, 100% { opacity: 1; } 50% { opacity: .25; } }
.anim-float { animation: d-float 2.4s ease-in-out infinite; }
@keyframes d-float { 0%, 100% { transform: translateY(0); } 50% { transform: translateY(-4px); } }
.anim-pulse { animation: d-pulse 1.5s ease-in-out infinite; transform-origin: center; }
@keyframes d-pulse { 0%, 100% { transform: scale(1); opacity: 1; } 50% { transform: scale(1.06); opacity: .75; } }

/* ---------------- quiz mode ---------------- */

.quiz-wrap { max-width: 860px; }
.quiz-top {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 18px;
  padding: 13px 18px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  font-size: 13px;
  color: var(--muted);
}
.quiz-top strong { color: var(--ink); }
.quiz-top .qcount { font-family: var(--font-mono); font-size: 12px; }
.quiz-top .spacer { margin-left: auto; }
.quiz-bar { height: 6px; width: 140px; border-radius: 999px; background: var(--surface-3); overflow: hidden; }
.quiz-bar i { display: block; height: 100%; background: linear-gradient(90deg, var(--leaf), var(--slate)); border-radius: 999px; transition: width .3s; }

.quiz-card .answer, .quiz-card .qblock, .quiz-card .diagram, .quiz-card .qlinks,
.quiz-card .analogy, .quiz-card .rate-wrap { display: none; }
.quiz-card.is-revealed .answer,
.quiz-card.is-revealed .qblock,
.quiz-card.is-revealed .diagram,
.quiz-card.is-revealed .rate-wrap { display: block; }
.quiz-card.is-revealed .qlinks { display: flex; }
.quiz-card.is-revealed .analogy { display: flex; }

.rate-wrap { margin-top: 20px; }
.qcard.is-learn .rate-wrap { display: block; }
.rate-label {
  font-size: 11px;
  font-weight: 800;
  letter-spacing: .09em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 9px;
}

.reveal-row { display: flex; gap: 10px; margin-top: 18px; flex-wrap: wrap; }
.btn {
  appearance: none;
  border: 1px solid transparent;
  font: inherit;
  font-size: 14px;
  font-weight: 700;
  padding: 10px 20px;
  border-radius: 12px;
  cursor: pointer;
  transition: transform .15s, box-shadow .15s, background .15s, border-color .15s;
}
.btn:active { transform: translateY(1px); }
.btn-primary {
  background: var(--brass-bright);
  color: var(--on-brass);
  box-shadow: 0 6px 16px -8px color-mix(in srgb, var(--brass-bright) 80%, transparent);
}
.btn-primary:hover { background: color-mix(in srgb, var(--brass-bright) 88%, #000); }
[data-theme="dark"] .btn-primary:hover { background: color-mix(in srgb, var(--brass-bright) 86%, #fff); }
.btn-ghost { background: var(--surface); border-color: var(--line-strong); color: var(--ink-2); }
.btn-ghost:hover { color: var(--ink); border-color: var(--muted); }

.rate-row { display: none; gap: 9px; margin-top: 20px; flex-wrap: wrap; }
.is-revealed .rate-row { display: flex; }
.qcard.is-learn .rate-row { display: flex; }   /* Learn mode shows the rating buttons without a reveal step */
.rate-btn {
  flex: 1 1 130px;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 2px;
  padding: 11px 15px;
  border-radius: 13px;
  border: 1.5px solid var(--line);
  background: var(--surface);
  cursor: pointer;
  font: inherit;
  color: var(--ink);
  text-align: left;
  transition: all .17s;
}
.rate-btn b { font-size: 14px; color: var(--ink); }
.rate-btn span { font-size: 12px; color: var(--ink-2); }
.rate-btn[data-rate="missed"] { border-color: color-mix(in srgb, var(--oxblood) 55%, var(--line)); }
.rate-btn[data-rate="shaky"]  { border-color: color-mix(in srgb, var(--brass) 55%, var(--line)); }
.rate-btn[data-rate="got"]    { border-color: color-mix(in srgb, var(--leaf) 55%, var(--line)); }
.rate-btn:hover { transform: translateY(-2px); box-shadow: var(--shadow); }
.rate-btn[data-rate="missed"]:hover { border-color: var(--oxblood); background: var(--oxblood-soft); }
.rate-btn[data-rate="shaky"]:hover  { border-color: var(--brass); background: var(--brass-soft); }
.rate-btn[data-rate="got"]:hover    { border-color: var(--leaf);  background: var(--leaf-soft); }
.rate-btn.is-picked[data-rate="missed"] { border-color: var(--oxblood); background: var(--oxblood-soft); }
.rate-btn.is-picked[data-rate="shaky"]  { border-color: var(--brass); background: var(--brass-soft); }
.rate-btn.is-picked[data-rate="got"]    { border-color: var(--leaf);  background: var(--leaf-soft); }

.quiz-done {
  text-align: center;
  padding: 56px 30px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow);
}
.quiz-done .big { font-size: 46px; line-height: 1; margin-bottom: 14px; }
.quiz-done h2 { font-family: var(--font-display); font-size: 27px; margin: 0 0 8px; }
.quiz-done p { color: var(--muted); margin: 0 0 22px; }
.done-stats { display: flex; justify-content: center; gap: 12px; margin-bottom: 24px; flex-wrap: wrap; }
.done-stat { background: var(--surface-2); border: 1px solid var(--line); border-radius: 14px; padding: 12px 20px; min-width: 92px; }
.done-stat b { display: block; font-family: var(--font-round); font-size: 23px; }
.done-stat span { font-size: 11.5px; color: var(--muted); }

/* ---------------- search results ---------------- */

.search-head .lede { margin-bottom: 16px; }
.search-head .btn { margin-bottom: 6px; }

.search-group { margin-top: 28px; }
.search-group-head {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 0 2px 10px;
  margin-bottom: 14px;
  border-bottom: 1px dashed var(--line-strong);
  text-decoration: none;
  color: var(--ink);
  font-family: var(--font-round);
  font-size: 15px;
}
.search-group-head:hover strong { color: var(--green); }
.search-group-head .nav-num { font-family: var(--font-mono); font-size: 11px; color: var(--muted); }
.search-group-head .sg-count {
  margin-left: auto;
  font-family: var(--font-body);
  font-size: 11.5px;
  font-weight: 500;
  color: var(--muted);
}

/* ---------------- misc ---------------- */

.empty {
  text-align: center;
  padding: 60px 20px;
  color: var(--muted);
}
.empty .big { font-size: 40px; margin-bottom: 12px; }

.toast {
  position: fixed;
  left: 50%;
  bottom: 26px;
  transform: translate(-50%, 20px);
  background: var(--ink);
  color: var(--bg);
  font-size: 13px;
  font-weight: 600;
  padding: 9px 18px;
  border-radius: 999px;
  opacity: 0;
  pointer-events: none;
  transition: all .25s;
  z-index: 100;
}
.toast.is-on { opacity: 1; transform: translate(-50%, 0); }

.site-foot {
  border-top: 1px solid var(--line);
  padding: 22px clamp(14px, 3vw, 30px) 40px;
  text-align: center;
  font-size: 12px;
  color: var(--muted);
}
.site-foot p { margin: 0; }

.sr-only {
  position: absolute; width: 1px; height: 1px;
  padding: 0; margin: -1px; overflow: hidden;
  clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}

/* ---------------- responsive ---------------- */

@media (max-width: 900px) {
  :root { --sidebar-w: 0px; }
  .layout { grid-template-columns: minmax(0, 1fr); }
  .sidebar {
    position: fixed;
    top: var(--topbar-h);
    left: 0; right: 0; bottom: 0;
    z-index: 40;
    max-height: none;
    overflow-y: auto;
    padding: 16px clamp(14px, 4vw, 28px) 40px;
    background: var(--bg);
    border-top: 1px solid var(--line);
    display: none;
  }
  .sidebar.is-open { display: block; }
  body:has(.sidebar.is-open) { overflow: hidden; }
  .menu-btn { display: grid; }
  .view { padding-top: 20px; }
  .brand-text small { display: none; }
  .search { width: 140px; }
}

@media (max-width: 640px) {
  .topbar { gap: 6px; padding: 0 10px; }
  .tools { gap: 5px; }
  .tools .icon-btn { width: 34px; height: 34px; }
  .tools .search { height: 34px; }
  .modes { padding: 3px; }
  .brand-text { display: none; }
  .modes { margin-left: 0; }
  .mode-btn { padding: 6px 9px; font-size: 12.5px; }
  .search { width: 38px; padding: 0 11px; }
  .search input { display: none; }
  .search:focus-within { width: 150px; }
  .search:focus-within input { display: block; }
  .hero { padding: 24px 20px; }
  .qcard { border-radius: var(--radius); }
  .qcard::before { border-radius: var(--radius) 0 0 var(--radius); }
  .analogy, .mental-model { font-size: 13.4px; }
}

/* roomier hit areas on touch devices */
@media (pointer: coarse) {
  .chip, .dbtn, .mode-btn, .nav-link, .icon-btn, .sp-reset { min-height: 44px; }
  .dots button { width: 34px; height: 34px; }
  .dots button.is-on { width: 44px; }
  .codeblock .copy { min-height: 34px; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: .001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .001ms !important;
    scroll-behavior: auto !important;
  }
}

/* ---------------- print ---------------- */

@media print {
  .topbar, .sidebar, .filters, .diagram-foot, .progress-rail, .site-foot, .rate-row, .reveal-row { display: none !important; }
  body { background: #fff; color: #000; font-size: 11pt; }
  .layout { display: block; padding: 0; }
  .view { max-width: none; padding: 0; }
  .qcard { break-inside: avoid; box-shadow: none; border: 1px solid #ccc; margin-bottom: 12px; }
  .qcard .answer, .qcard .qblock, .qcard .diagram { display: block !important; }
  .diagram { break-inside: avoid; }
}

/* ============================================================
   Interactive layer — clusters, predict-first, labs, step-through
   ============================================================ */

.mono { font-family: var(--font-mono); }
.btn-sm { font-size: 12.5px; padding: 7px 14px; border-radius: 10px; }
.btn:disabled { opacity: .45; cursor: not-allowed; transform: none; }
.btn-ghost.mono { font-size: 12px; font-weight: 600; }

/* ---------- numbering ---------- */
.qbank {
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 10.5px;
  color: var(--muted);
  border: 1px dashed var(--line-strong);
  border-radius: 6px;
  padding: 1px 6px;
}

/* ---------- clusters ---------- */
.cluster { margin-top: 8px; }
.cluster + .cluster { margin-top: 34px; }
.cluster-head { margin: 0 4px 16px; position: relative; padding-left: 16px; }
.cluster-head::before {
  content: "";
  position: absolute;
  left: 0; top: 4px; bottom: 4px;
  width: 4px;
  border-radius: 4px;
  background: linear-gradient(var(--green), var(--slate));
}
.cluster-head h2 { font-family: var(--font-display); font-size: 21px; margin: 2px 0 2px; letter-spacing: -.01em; }
.cluster-head p { margin: 0; font-size: 14px; color: var(--ink-2); }
.cluster-range { font-family: var(--font-mono); font-size: 11px; color: var(--green); font-weight: 700; }
.cluster-meta { display: block; margin-top: 4px; font-size: 11.5px; color: var(--muted); }

.cluster-map { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 16px; }
.cluster-chip {
  appearance: none;
  font: inherit;
  font-size: 12.5px;
  font-weight: 600;
  color: var(--ink-2);
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 5px 13px 5px 5px;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 7px;
  transition: transform .15s, border-color .15s, color .15s;
}
.cluster-chip b {
  display: inline-grid;
  place-items: center;
  min-width: 22px; height: 22px;
  border-radius: 999px;
  background: var(--green-soft);
  color: var(--green);
  font-size: 11px;
}
.cluster-chip:hover { transform: translateY(-1px); border-color: var(--green); color: var(--ink); }

/* ---------- predict first ---------- */
.predict {
  margin: 0 0 18px;
  padding: 14px 16px;
  border-radius: 16px;
  background: color-mix(in srgb, var(--green) 7%, var(--surface));
  border: 1px solid color-mix(in srgb, var(--green) 24%, var(--line));
}
.predict-label {
  font-size: 11px;
  font-weight: 800;
  letter-spacing: .09em;
  text-transform: uppercase;
  color: var(--green);
  margin-bottom: 8px;
}
.predict-item + .predict-item { margin-top: 14px; padding-top: 14px; border-top: 1px dashed var(--line-strong); }
.predict-prompt { margin: 0 0 7px; font-weight: 700; font-size: 14.5px; }
.predict-code {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 11px;
  padding: 10px 13px;
  font-size: 12.8px;
  line-height: 1.55;
  overflow-x: auto;
}
.predict-code code, .lab-line code { background: none; border: 0; padding: 0; white-space: pre; }
.predict-explain {
  margin-top: 10px;
  padding: 9px 12px;
  border-radius: 11px;
  font-size: 13.8px;
  color: var(--ink-2);
  animation: d-fade .35s ease both;
}

.pick-row { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 10px; }
.pick {
  appearance: none;
  font: inherit;
  font-size: 13.5px;
  font-weight: 700;
  color: var(--ink);
  background: var(--surface);
  border: 1.5px solid var(--line-strong);
  border-radius: 11px;
  padding: 7px 16px;
  cursor: pointer;
  transition: transform .14s, border-color .14s, background .14s;
}
.pick:hover:not(:disabled) { transform: translateY(-2px); border-color: var(--green); }
.pick:disabled { cursor: default; opacity: .55; }
.pick.is-right { opacity: 1; border-color: var(--leaf); background: var(--leaf-soft); color: var(--leaf); animation: pick-pop .4s cubic-bezier(.2, 1.4, .4, 1); }
.pick.is-wrong { opacity: 1; border-color: var(--oxblood); background: var(--oxblood-soft); color: var(--oxblood); animation: pick-shake .4s ease; }
@keyframes pick-pop { 0% { transform: scale(.94); } 60% { transform: scale(1.06); } 100% { transform: scale(1); } }
@keyframes pick-shake { 0%, 100% { transform: translateX(0); } 25% { transform: translateX(-5px); } 75% { transform: translateX(5px); } }


/* ---------- comparison table ---------- */
.cmp-wrap { margin: 0 0 18px; overflow-x: auto; }
/* right-edge fade while more columns are off-screen (class toggled by updateCmpFades) */
.cmp-wrap.has-more { -webkit-mask-image: linear-gradient(to right, #000 calc(100% - 44px), transparent); mask-image: linear-gradient(to right, #000 calc(100% - 44px), transparent); }
mark { background: color-mix(in srgb, var(--brass-bright) 38%, transparent); color: inherit; border-radius: 3px; padding: 0 1px; }
.cmp { width: 100%; border-collapse: separate; border-spacing: 0; font-size: 13.4px; }
.cmp th, .cmp td { padding: 8px 11px; text-align: left; border-bottom: 1px solid var(--line); transition: background .18s, opacity .18s; }
.cmp tbody th { font-weight: 600; color: var(--ink-2); white-space: nowrap; }
.cmp td { color: var(--ink); }
.cmp td.is-yes { color: var(--leaf); font-weight: 700; }
.cmp td.is-no { color: var(--muted); }
.cmp-col {
  appearance: none;
  font: 700 12.5px var(--font-mono);
  color: var(--green);
  background: var(--green-soft);
  border: 0;
  border-radius: 8px;
  padding: 6px 11px;
  min-height: 24px;
  cursor: pointer;
}
.cmp[data-focus] td:not(.is-focus) { opacity: .35; }
.cmp .is-focus { background: color-mix(in srgb, var(--green) 9%, transparent); }
.cmp-hint { margin: 6px 0 0; font-size: 11.5px; color: var(--muted); }

/* ---------- labs ---------- */
.lab {
  margin: 20px 0 4px;
  border-radius: var(--radius);
  border: 1px solid color-mix(in srgb, var(--accent, var(--green)) 30%, var(--line));
  background:
    radial-gradient(circle at 1px 1px, var(--bg-dot) 1px, transparent 0) 0 0 / 18px 18px,
    var(--surface-2);
  overflow: hidden;
}
.lab-head {
  display: flex;
  align-items: center;
  gap: 9px;
  padding: 10px 14px;
  border-bottom: 1px solid var(--line);
  background: color-mix(in srgb, var(--surface) 76%, transparent);
}
.lab-badge {
  font-size: 10px;
  font-weight: 800;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--leaf);
  background: var(--leaf-soft);
  border-radius: 6px;
  padding: 2px 7px;
}
.lab-hint { margin: 10px 16px 0; font-size: 13px; color: var(--muted); }
.lab-body { padding: 12px 16px 16px; }
.lab-grid { display: grid; grid-template-columns: minmax(0, .62fr) minmax(0, 1.38fr); gap: 16px; align-items: center; }
.lab-stage svg, .diagram-body .diagram-stage svg { width: 100%; height: auto; display: block; overflow: visible; }
/* labs and step-throughs share their width with code, so their labels run larger */
.lab-stage .d-t-b, .diagram-body .d-t-b { font-size: 15px; }
.lab-stage .d-t-sm, .diagram-body .d-t-sm { font-size: 12.5px; }
.lab-stage .d-t-mono, .diagram-body .d-t-mono { font-size: 13.5px; }
.lab-stage .d-t-w, .diagram-body .d-t-w { font-size: 12px; }
.lab-code, .diagram-code {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 8px 0;
  font-family: var(--font-mono);
  font-size: 12.3px;
  line-height: 1.5;
  overflow-x: auto;
}
.lab-line { padding: 1px 12px; white-space: pre; border-left: 3px solid transparent; transition: background .2s, opacity .2s; }
.lab-line.is-todo { opacity: .38; }
.lab-line.is-next {
  background: color-mix(in srgb, var(--brass) 16%, transparent);
  border-left-color: var(--brass);
}
.lab-out {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  margin-top: 12px;
  padding: 9px 12px;
  border-radius: 11px;
  font-size: 13.6px;
  color: var(--ink-2);
  background: var(--surface);
  border: 1px solid var(--line);
  animation: d-fade .3s ease both;
}
.lab-out code { font-weight: 700; }
.lab-count { margin-left: auto; font-family: var(--font-mono); font-size: 11.5px; color: var(--muted); }
.lab-count b { color: var(--ink); }
.lab-nudge { margin: 8px 2px 0; font-size: 13px; color: var(--muted); }
.lab-actions { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 12px; }

.seg {
  display: inline-flex;
  padding: 3px;
  border-radius: 11px;
  background: var(--surface-3);
  margin-bottom: 12px;
}
.seg button {
  appearance: none;
  border: 0;
  background: transparent;
  font: 700 12.5px var(--font-mono);
  color: var(--ink-2);
  padding: 6px 16px;
  border-radius: 9px;
  cursor: pointer;
}
.seg button.is-on { background: var(--surface); color: var(--green); box-shadow: var(--shadow-sm); }

.lab-out.is-ok, .predict-explain.is-ok { background: var(--leaf-soft); border: 1px solid color-mix(in srgb, var(--leaf) 30%, transparent); }
.lab-out.is-hot, .predict-explain.is-hot { background: var(--oxblood-soft); border: 1px solid color-mix(in srgb, var(--oxblood) 26%, transparent); }

/* game + decision */
.game-top { display: flex; align-items: center; justify-content: center; gap: 14px; margin: 12px 0; }
.game-dots { display: flex; gap: 5px; }
.game-dots i { width: 8px; height: 8px; border-radius: 50%; background: var(--line-strong); transition: background .2s, transform .2s; }
.game-dots i.is-done { background: var(--leaf); }
.game-dots i.is-on { background: var(--green); transform: scale(1.3); }
.game-q { font-size: 15.5px; font-weight: 600; margin: 12px 0 2px; }
.game-done { text-align: center; padding: 10px 0 4px; }
.game-score { font-family: var(--font-round); font-size: 44px; font-weight: 800; color: var(--green); line-height: 1; }
.game-score span { font-size: 18px; color: var(--muted); margin-left: 4px; }
.game-done p { color: var(--ink-2); font-size: 14px; }

.crumbs { display: flex; flex-wrap: wrap; align-items: center; gap: 6px; margin-bottom: 4px; }
.crumb { font-size: 12px; color: var(--ink-2); background: var(--surface); border: 1px solid var(--line); border-radius: 999px; padding: 3px 10px; animation: d-fade .3s ease both; }
.crumb b { margin-left: 3px; text-transform: uppercase; font-size: 10.5px; }
.crumb b.is-yes { color: var(--leaf); background: none; border: 0; }
.crumb b.is-no { color: var(--oxblood); background: none; border: 0; }
.crumb-sep { color: var(--muted); font-size: 12px; }
.verdict { margin-top: 10px; padding: 14px 16px; border-radius: 14px; background: var(--surface); border: 1px solid var(--line); }
.verdict-kw { font-size: 24px; font-weight: 800; color: var(--green); }
.verdict p { margin: 6px 0 0; font-size: 14px; color: var(--ink-2); }
.verdict-then { padding-top: 8px; border-top: 1px dashed var(--line); }

/* ---------- step-through diagrams ---------- */
.diagram-body { display: grid; grid-template-columns: minmax(0, .85fr) minmax(0, 1.15fr); gap: 12px; align-items: center; padding: 12px 14px 2px; }
.diagram-body .diagram-stage { padding: 0; min-height: 0; }

/* ---------- predict gate ---------- */
.qbody { transition: filter .35s ease, opacity .35s ease; }
.qcard.is-gated .qbody {
  max-height: 170px;
  overflow: hidden;
  filter: blur(5px);
  opacity: .5;
  user-select: none;
  -webkit-mask-image: linear-gradient(#000 25%, transparent);
  mask-image: linear-gradient(#000 25%, transparent);
}
.gate {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 6px 14px;
  margin-top: -64px;
  position: relative;
  padding: 12px 16px;
  border-radius: 14px;
  background: var(--surface);
  border: 1px dashed var(--line-strong);
  font-size: 13.5px;
  font-weight: 600;
  color: var(--ink-2);
  text-align: center;
}
.gate-skip {
  appearance: none;
  border: 0;
  background: none;
  font: inherit;
  font-size: 12.5px;
  color: var(--green);
  text-decoration: underline;
  text-underline-offset: 2px;
  cursor: pointer;
  padding: 4px 2px;
}

/* ---------- sidebar extras ---------- */
.ring { margin-left: auto; flex-shrink: 0; transform: rotate(-90deg); }
.ring-bg { fill: none; stroke: var(--surface-3); stroke-width: 2.6; }
.ring-fg { fill: none; stroke: var(--leaf); stroke-width: 2.6; stroke-linecap: round; transition: stroke-dashoffset .6s ease; }
.ring-done {
  margin-left: auto;
  display: inline-grid;
  place-items: center;
  width: 17px; height: 17px;
  border-radius: 50%;
  background: var(--leaf);
  color: var(--surface);
  font-size: 10px;
  font-weight: 800;
}
.streak-on { color: var(--brass) !important; }

/* ---------- related links ---------- */
.qlinks-label { font-size: 11px; font-weight: 800; letter-spacing: .09em; text-transform: uppercase; color: var(--muted); align-self: center; margin-right: 2px; }
.qlinks a b { font-family: var(--font-mono); color: var(--green); margin-right: 3px; }

/* ---------- motion ---------- */
.confetti { position: fixed; inset: 0; width: 100vw; height: 100vh; pointer-events: none; z-index: 200; }

/* quiz: labs and tables are part of the answer; predicts stay as the warm-up */
.quiz-card .lab, .quiz-card .cmp-wrap { display: none; }
.quiz-card.is-revealed .lab, .quiz-card.is-revealed .cmp-wrap { display: block; }

@media (max-width: 760px) {
  .lab-grid, .diagram-body { grid-template-columns: minmax(0, 1fr); }
  .qbank { margin-left: 0; }
  /* the SVG scales down to ~60% here, so grow its labels to stay readable */
  .lab-stage .d-t-b, .diagram-body .d-t-b { font-size: 18px; }
  .lab-stage .d-t-sm, .diagram-body .d-t-sm { font-size: 14px; }
  .lab-stage .d-t-mono, .diagram-body .d-t-mono { font-size: 15px; }
  .lab-stage .d-t-w, .diagram-body .d-t-w { font-size: 13px; }
}

@media print {
  .lab, .cluster-map, .predict .pick-row, .gate { display: none !important; }
  .qcard.is-gated .qbody { max-height: none; filter: none; opacity: 1; -webkit-mask-image: none; mask-image: none; }
}

/* ============================================================
   Motion — page transitions and small, purposeful feedback
   ============================================================ */

/* Only the main column cross-fades between views; topbar and sidebar swap in place. */
.view { view-transition-name: main-view; }
::view-transition-old(root),
::view-transition-new(root) { animation: none; }
::view-transition-old(main-view) { animation: vt-out .16s ease-in both; }
::view-transition-new(main-view) { animation: vt-in .34s var(--ease-out) both; }
::view-transition-group(main-view) { animation-duration: .34s; }
@keyframes vt-out { to { opacity: 0; transform: translateY(-6px); } }
@keyframes vt-in { from { opacity: 0; transform: translateY(12px); } }

/* press feedback */
.btn:active, .pick:active:not(:disabled), .chip:active, .dbtn:active:not(:disabled),
.rate-btn:active, .cluster-chip:active, .mode-btn:active, .seg button:active, .cmp-col:active {
  transform: scale(.96);
}
.pick, .chip, .dbtn, .mode-btn, .seg button, .cmp-col { transition: transform .14s var(--ease-out), background .16s, border-color .16s, color .16s; }

/* sidebar links nudge toward the content */
.nav-link { transition: background .16s, color .16s, transform .2s var(--ease-out); }
.nav-link:hover { transform: translateX(3px); }

/* drawn underline on text links */
.backlink, .gate-skip {
  background-image: linear-gradient(currentColor, currentColor);
  background-size: 0 1px;
  background-position: 0 100%;
  background-repeat: no-repeat;
  transition: background-size .28s var(--ease-out), color .16s, border-color .16s;
}
.backlink:hover, .gate-skip:hover { background-size: 100% 1px; }
.gate-skip { text-decoration: none; background-size: 100% 1px; }
.gate-skip:hover { background-size: 30% 1px; }

/* the explanation un-blurs instead of snapping open */
.qcard .qbody { transition: filter .45s var(--ease-out), opacity .45s var(--ease-out); }

@media (prefers-reduced-motion: reduce) {
  ::view-transition-old(main-view), ::view-transition-new(main-view) { animation: none; }
  .nav-link:hover { transform: none; }
}

/* Labs and step-throughs stack code over picture whenever they are narrow,
   whatever the window size (sidebar + card padding can squeeze them on laptops). */
.lab-body, .diagram.has-code { container-type: inline-size; }
@container (max-width: 600px) {
  .lab-grid, .diagram-body { grid-template-columns: minmax(0, 1fr); }
}

/* ---------- labs: access + graphemes ---------- */
.seg { flex-wrap: wrap; max-width: 100%; }
.seg + .seg { vertical-align: top; }

.acc-list { list-style: none; margin: 12px 0 0; padding: 0; display: grid; gap: 6px; }
.acc-row {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 12px;
  border-radius: 11px;
  font-size: 13.6px;
  background: var(--surface);
  border: 1px solid var(--line);
  transition: background .25s, border-color .25s, color .25s;
}
.acc-row.is-yes { border-color: color-mix(in srgb, var(--leaf) 35%, var(--line)); background: var(--leaf-soft); color: var(--ink); }
.acc-row.is-no { color: var(--muted); }
.acc-mark {
  display: inline-grid;
  place-items: center;
  width: 20px; height: 20px;
  border-radius: 50%;
  font-size: 11px;
  font-weight: 800;
  flex-shrink: 0;
  transition: background .25s, color .25s, transform .3s var(--ease-out);
}
.acc-row.is-yes .acc-mark { background: var(--leaf); color: var(--surface); transform: scale(1.05); }
.acc-row.is-no .acc-mark { background: var(--surface-3); color: var(--muted); }

.g-input {
  width: 100%;
  margin-top: 12px;
  font: 500 20px var(--font-body);
  color: var(--ink);
  background: var(--surface);
  border: 1.5px solid var(--line-strong);
  border-radius: 12px;
  padding: 10px 14px;
  outline: none;
  transition: border-color .16s, box-shadow .16s;
}
.g-input:focus { border-color: var(--green); box-shadow: 0 0 0 3px color-mix(in srgb, var(--green) 18%, transparent); }
.g-stats { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 8px; margin-top: 12px; }
.g-stat { background: var(--surface); border: 1px solid var(--line); border-radius: 12px; padding: 9px 11px; min-width: 0; }
.g-stat b { display: block; font: 700 22px var(--font-display); color: var(--ink); }
.g-stat:first-child b { color: var(--green); }
.g-stat span { display: block; font-size: 12px; color: var(--ink-2); }
.g-stat code { font-size: 10.5px; background: none; border: 0; padding: 0; color: var(--muted); white-space: normal; }
.g-chars { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 12px; }
.g-char {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  padding: 8px 10px;
  border-radius: 12px;
  background: var(--surface);
  border: 1px solid var(--line);
  animation: d-pop .35s var(--ease-out) both;
}
.g-glyph { font-size: 24px; line-height: 1.1; }
.g-scalars { font-family: var(--font-mono); font-size: 10.5px; color: var(--muted); max-width: 150px; text-align: center; }

@container (max-width: 600px) {
  .g-stats { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

/* ---------- topic switcher ---------- */
.topic-switch { display: flex; flex-wrap: wrap; gap: 6px; padding: 0 12px 14px; }
.topic-switch .chip { text-decoration: none; padding: 4px 11px; font-size: 12px; }

/* ---------- Topic 2 labs ---------- */
.cells-label { margin: 12px 0 6px; font-size: 11.5px; font-weight: 700; letter-spacing: .05em; text-transform: uppercase; color: var(--muted); }
.cells-label code { text-transform: none; letter-spacing: 0; }
.cells { display: flex; gap: 8px; flex-wrap: wrap; }
.cell {
  position: relative;
  overflow: hidden;
  min-width: 56px;
  padding: 8px 12px 6px;
  border-radius: 12px;
  background: var(--surface);
  border: 1px solid var(--line);
  text-align: center;
  opacity: .5;
  transition: opacity .3s, background .3s, border-color .3s, transform .3s var(--ease-out);
}
.cell b { display: block; font: 700 18px var(--font-display); color: var(--ink); position: relative; z-index: 1; }
.cell i { display: block; font: 500 11px var(--font-mono); color: var(--muted); font-style: normal; position: relative; z-index: 1; }
.cell.is-in { opacity: 1; background: var(--slate-soft); border-color: color-mix(in srgb, var(--slate) 40%, var(--line)); transform: translateY(-2px); }
.cell.is-hot { background: var(--brass-soft); border-color: color-mix(in srgb, var(--brass) 45%, var(--line)); }
.cell-bar { position: absolute; left: 0; right: 0; bottom: 0; background: color-mix(in srgb, var(--brass) 18%, transparent); transition: height .35s var(--ease-out); }

.lab-check { display: inline-flex; align-items: center; gap: 8px; margin: 0 0 10px 6px; font-size: 13px; color: var(--ink-2); cursor: pointer; }
.lab-check input { accent-color: var(--green); width: 16px; height: 16px; }
.lab-range { display: flex; align-items: center; gap: 12px; margin: 4px 0 12px; font-size: 13px; color: var(--ink-2); }
.lab-range input { flex: 1; accent-color: var(--green); }

.kv { display: grid; grid-template-columns: minmax(0, 1.2fr) minmax(0, 1fr); gap: 1px; margin-top: 8px; background: var(--line); border: 1px solid var(--line); border-radius: 12px; overflow: hidden; font-size: 13px; }
.kv > span, .kv > b { background: var(--surface); padding: 7px 12px; min-width: 0; overflow-wrap: anywhere; }
.kv > span { color: var(--ink-2); font-family: var(--font-mono); font-size: 12px; }
.kv > b { font-weight: 600; color: var(--ink); }
.kv > b.is-nil { color: var(--muted); font-weight: 500; font-style: italic; }
.kv > b.is-hot-text { color: var(--oxblood); }
.kv-wide { grid-template-columns: minmax(0, .8fr) minmax(0, 1.6fr); }

.zone-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(118px, 1fr)); gap: 8px; margin-top: 6px; }
.zone-card { display: flex; flex-direction: column; gap: 1px; padding: 9px 12px; border-radius: 12px; background: var(--surface); border: 1px solid var(--line); transition: border-color .25s, background .25s; }
.zone-card.is-other { border-color: color-mix(in srgb, var(--brass) 55%, var(--line)); background: var(--brass-soft); }
.zone-name { font-size: 11.5px; font-weight: 700; letter-spacing: .04em; text-transform: uppercase; color: var(--muted); }
.zone-card b { font: 700 22px var(--font-display); color: var(--ink); }
.zone-card span:not(.zone-name) { font: 500 12px var(--font-mono); color: var(--ink-2); }
.zone-card em { font-size: 11.5px; color: var(--muted); font-style: normal; }

.snake-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 10px; margin-top: 10px; }
.snake-grid label { display: block; font-size: 11.5px; font-weight: 700; letter-spacing: .05em; text-transform: uppercase; color: var(--muted); }
.snake-grid .g-input { margin-top: 5px; font: 500 15px var(--font-mono); }

.pick.is-on-pick { border-color: var(--green); background: var(--green-soft); color: var(--green); }
.locale-rows { display: grid; gap: 6px; margin-top: 10px; }
.locale-row { display: grid; grid-template-columns: minmax(0, .9fr) minmax(0, 1.4fr) minmax(0, 1.1fr); gap: 4px 12px; align-items: center; padding: 8px 12px; border-radius: 12px; background: var(--surface); border: 1px solid var(--line); }
.lr-in { font: 500 12px var(--font-mono); color: var(--muted); }
.lr-out { font: 600 15px var(--font-body); color: var(--ink); overflow-wrap: anywhere; }
.locale-row code { background: none; border: 0; padding: 0; font-size: 10.5px; color: var(--muted); white-space: normal; }

@container (max-width: 600px) {
  .locale-row { grid-template-columns: 1fr; }
  .kv, .kv-wide { grid-template-columns: minmax(0, 1fr); }
  .kv > span { padding-bottom: 0; }
}

/* ---------- Topic 3 labs ---------- */
.byte-grid { display: grid; gap: 5px; margin-top: 4px; }
.byte-row { display: flex; align-items: center; gap: 4px; }
.byte-row > i { width: 30px; flex-shrink: 0; font: 500 11px var(--font-mono); color: var(--muted); font-style: normal; text-align: right; padding-right: 6px; }
.byte {
  display: inline-grid;
  place-items: center;
  width: 30px; height: 30px;
  border-radius: 7px;
  font: 700 11px var(--font-mono);
  color: var(--surface);
  animation: d-pop .3s var(--ease-out) both;
}
.byte.pad { background: transparent; border: 1.5px dashed var(--line-strong); color: var(--muted); font-weight: 500; }
.byte.f0 { background: var(--green); }
.byte.f1 { background: var(--brass); }
.byte.f2 { background: var(--slate); }
.byte.f3 { background: var(--plum); }
.byte.f4 { background: var(--oxblood); }
.byte.f5 { background: var(--leaf); }

.bar-track { height: 10px; margin: 10px 0 4px; border-radius: 999px; background: var(--surface-3); overflow: hidden; }
.bar-track > i { display: block; height: 100%; border-radius: 999px; background: var(--leaf); transition: width .35s var(--ease-out), background .25s; }
.bar-track > i.is-hot { background: var(--oxblood); }

/* ---------- Topic 4 labs ---------- */
.mro { display: flex; flex-wrap: wrap; align-items: center; gap: 6px; margin: 10px 0; }
.mro-box { position: relative; padding: 8px 14px; border-radius: 11px; background: var(--surface); border: 1px solid var(--line-strong); font: 700 13px var(--font-mono); color: var(--ink); transition: background .25s, border-color .25s; }
.mro-box i { display: block; margin-top: 2px; font: 500 11px var(--font-mono); color: var(--green); font-style: normal; }
.mro-box.is-hit { background: var(--leaf-soft); border-color: var(--leaf); }
.mro-arrow { font-size: 11px; color: var(--muted); }
.steps { margin: 6px 0 0; padding: 0 0 0 22px; font-size: 13.5px; color: var(--ink-2); }
.steps li { padding: 3px 0; animation: d-fade .3s ease both; }
.steps li.is-ok { color: var(--ink); }
.steps li.is-hot { color: var(--oxblood); font-weight: 600; }
.imp-table { display: grid; gap: 6px; margin: 4px 0 8px; }
.imp-row { display: flex; align-items: center; gap: 12px; padding: 8px 12px; border-radius: 11px; background: var(--surface); border: 1px solid var(--line); transition: background .3s, border-color .3s; }
.imp-row.is-swapped { background: var(--brass-soft); border-color: color-mix(in srgb, var(--brass) 45%, var(--line)); }
.imp-row code { min-width: 62px; background: none; border: 0; padding: 0; font-weight: 700; }
.imp-arrow { color: var(--muted); }
.imp-row b { font: 600 13px var(--font-mono); color: var(--ink); }

/* ---------- Topic 5 labs ---------- */
.stage-row { display: flex; flex-wrap: wrap; align-items: stretch; gap: 6px; margin: 12px 0 10px; }
.stage { display: flex; flex-direction: column; gap: 2px; min-width: 96px; padding: 8px 11px; border-radius: 12px; background: var(--surface); border: 1.5px solid var(--line); transition: background .3s, border-color .3s, opacity .3s; }
.stage b { font-size: 12.5px; color: var(--ink); }
.stage code { background: none; border: 0; padding: 0; font-size: 10.5px; color: var(--muted); white-space: normal; }
.stage-mark { font: 800 13px var(--font-mono); }
.stage.is-ok { border-color: color-mix(in srgb, var(--leaf) 45%, var(--line)); background: var(--leaf-soft); }
.stage.is-ok .stage-mark { color: var(--leaf); }
.stage.is-fail, .stage.is-crash { border-color: var(--oxblood); background: var(--oxblood-soft); }
.stage.is-fail .stage-mark, .stage.is-crash .stage-mark { color: var(--oxblood); }
.stage.is-skip { opacity: .4; }
.stage-arrow { align-self: center; color: var(--muted); font-size: 12px; }

/* ---------- Topic 6 labs ---------- */
.cb-log { display: grid; gap: 5px; margin-top: 12px; }
.cb { display: flex; flex-wrap: wrap; align-items: baseline; gap: 4px 10px; padding: 7px 11px; border-radius: 11px; background: var(--surface); border: 1px solid var(--line); animation: d-fade .3s ease both; }
.cb-who { font: 800 10.5px var(--font-mono); letter-spacing: .06em; text-transform: uppercase; color: var(--green); min-width: 44px; }
.cb code { background: none; border: 0; padding: 0; font-size: 12.5px; white-space: normal; color: var(--ink); }
.cb i { font-size: 12px; color: var(--muted); font-style: normal; flex-basis: 100%; padding-left: 54px; }
.cb-none { border-style: dashed; background: var(--oxblood-soft); }
.cb-none .cb-who { color: var(--oxblood); }
.rl-steps { list-style: none; padding: 0; counter-reset: rl; }
.rl-steps li { counter-increment: rl; display: flex; gap: 10px; align-items: baseline; padding: 5px 10px; border-radius: 9px; }
.rl-steps li::before { content: counter(rl); font: 600 11px var(--font-mono); color: var(--muted); min-width: 16px; }
.rl-steps li b { font: 700 12.5px var(--font-mono); min-width: 110px; color: var(--ink); }
.rl-steps li span { font-size: 13px; color: var(--ink-2); }
.rl-steps li.is-last { background: var(--surface-2); }
.rl-steps li.is-dim b, .rl-steps li.is-dim span { color: var(--muted); }
.rl-steps li.is-hot b { color: var(--oxblood); }
.rl-steps li.is-ok b { color: var(--leaf); }

/* ---------- Topic 7 labs ---------- */
.ht-screen { position: relative; width: 300px; max-width: 100%; height: 180px; margin: 12px 0; border-radius: 14px; border: 1.5px solid var(--line); background: var(--surface-2); overflow: hidden; cursor: crosshair; }
.ht-view { position: absolute; display: flex; align-items: flex-start; padding: 4px 8px; border-radius: 8px; border: 1.5px solid; font: 700 11px var(--font-mono); pointer-events: none; transition: opacity .25s, box-shadow .25s; }
.ht-green { border-color: var(--green); background: color-mix(in srgb, var(--green) 14%, transparent); color: var(--green); }
.ht-brass { border-color: var(--brass); background: color-mix(in srgb, var(--brass) 25%, transparent); color: var(--ink); }
.ht-plum { border-color: var(--plum); background: color-mix(in srgb, var(--plum) 16%, transparent); color: var(--plum); }
.ht-view.is-dim { opacity: .25; }
.ht-view.is-hit { box-shadow: 0 0 0 3px var(--leaf); }
.ht-ext { position: absolute; border: 1.5px dashed var(--green); border-radius: 12px; pointer-events: none; opacity: .6; }
.ht-dot { position: absolute; width: 12px; height: 12px; margin: -6px 0 0 -6px; border-radius: 50%; background: var(--oxblood); box-shadow: 0 0 0 4px color-mix(in srgb, var(--oxblood) 25%, transparent); pointer-events: none; }
.btn.is-on { border-color: var(--green); color: var(--green); }
.cvl { width: 100%; max-width: 260px; margin: 10px 0; display: block; }
.cvl-bg { fill: var(--surface-2); stroke: var(--line); }
.cvl rect:not(.cvl-bg) { fill: color-mix(in srgb, var(--green) 22%, transparent); stroke: var(--green); stroke-width: 1; transition: all .3s; }
.cvl text { font: 700 10px var(--font-mono); fill: var(--ink); }
.cvl-knobs { display: grid; gap: 4px; margin-top: 8px; }
.lab-code { font: 12px var(--font-mono); padding: 8px 12px; border-radius: 10px; background: var(--surface); border: 1px solid var(--line); white-space: pre-wrap; }

/* ---------- Topic 8 labs ---------- */
.pl-stage { position: relative; margin: 12px 0; }
.pl-outer, .pl-inner, .pl-child { position: absolute; border-radius: 6px; transition: all .35s; }
.pl-outer { border: 1.5px dashed var(--brass); background: color-mix(in srgb, var(--brass) 10%, transparent); }
.pl-inner { border: 1.5px solid var(--plum); background: color-mix(in srgb, var(--plum) 10%, transparent); }
.pl-child { background: color-mix(in srgb, var(--green) 40%, transparent); border: 1.5px solid var(--green); }
.ident-card { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin: 12px 0; padding: 14px 18px; border-radius: 14px; border: 1.5px solid var(--line); background: var(--surface); transition: background .35s, border-color .35s; }
.ident-card b { font-size: 22px; }
.ident-card.is-a { border-color: var(--green); background: color-mix(in srgb, var(--green) 10%, var(--surface)); }
.ident-card.is-b { border-color: var(--brass); background: color-mix(in srgb, var(--brass) 14%, var(--surface)); }

/* ---------- Topic 9 labs ---------- */
.hug-row { display: flex; max-width: 100%; margin: 12px 0; border: 1.5px dashed var(--line); border-radius: 10px; overflow: hidden; }
.hug-lbl { display: flex; flex-direction: column; gap: 2px; padding: 8px 10px; min-width: 0; overflow: hidden; transition: width .35s; }
.hug-lbl b { font-size: 12px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.hug-lbl span { font: 600 10.5px var(--font-mono); color: var(--muted); }
.hug-lbl.is-a { background: color-mix(in srgb, var(--green) 16%, transparent); }
.hug-lbl.is-b { background: color-mix(in srgb, var(--brass) 22%, transparent); }
.fl-chart { position: relative; display: flex; align-items: flex-end; gap: 5px; margin: 12px 0; padding: 0 4px; border-bottom: 1.5px solid var(--line); max-width: 460px; }
.fl-col { flex: 1; display: flex; flex-direction: column-reverse; border-radius: 4px 4px 0 0; overflow: hidden; }
.fl-cpu { background: color-mix(in srgb, var(--green) 55%, transparent); transition: height .3s; }
.fl-gpu { background: color-mix(in srgb, var(--plum) 45%, transparent); transition: height .3s; }
.fl-col.is-bad { outline: 2px solid var(--oxblood); outline-offset: 1px; }
.fl-budget { position: absolute; left: 0; right: 0; border-top: 1.5px dashed var(--oxblood); pointer-events: none; transition: bottom .3s; }
.fl-budget span { position: absolute; right: 0; top: -17px; font: 700 10.5px var(--font-mono); color: var(--oxblood); }
.lm-track { position: relative; height: 56px; width: 320px; max-width: 100%; margin: 12px 0; border-bottom: 1.5px solid var(--line); }
.lm-box, .lm-ghost { position: absolute; top: 8px; width: 80px; height: 36px; border-radius: 8px; display: grid; place-items: center; font: 700 11px var(--font-mono); }
.lm-box { background: color-mix(in srgb, var(--green) 30%, transparent); border: 1.5px solid var(--green); transition: left .25s; }
.lm-ghost { border: 1.5px dashed var(--brass); color: var(--muted); transition: left .25s; }
.game-top .lab-count { margin-left: 0; }

/* ---------- Topic 10 labs ---------- */
.qt { margin: 12px 0; display: grid; gap: 6px; }
.qt-lane { display: flex; align-items: center; gap: 10px; }
.qt-lane > b { min-width: 76px; font: 700 11px var(--font-mono); color: var(--muted); }
.qt-track { position: relative; height: 30px; flex: 1; min-width: 0; border-bottom: 1px dashed var(--line); }
.qt-bar { position: absolute; top: 2px; height: 26px; border-radius: 7px; display: grid; place-items: center; font: 700 11px var(--font-mono); transition: left .3s, width .3s; }
.qt-bar.is-run { background: color-mix(in srgb, var(--green) 35%, transparent); border: 1.5px solid var(--green); }
.qt-bar.is-wait { background: color-mix(in srgb, var(--oxblood) 18%, transparent); border: 1.5px dashed var(--oxblood); color: var(--oxblood); }
.qt-bar.is-ok { background: color-mix(in srgb, var(--leaf) 30%, transparent); border: 1.5px solid var(--leaf); }
.ra-hot { background: color-mix(in srgb, var(--brass) 30%, transparent); display: inline-block; width: 100%; }
.lab-code span { display: block; }
.tt { display: grid; gap: 6px; margin: 12px 0; }
.tt-node { display: flex; flex-wrap: wrap; align-items: baseline; gap: 4px 12px; padding: 7px 12px; border-radius: 10px; border: 1.5px solid var(--line); background: var(--surface); transition: border-color .3s, background .3s; }
.tt-node b { font-size: 13px; }
.tt-node span { font-size: 12px; color: var(--muted); flex: 1; min-width: 120px; }
.tt-node code { background: none; border: 0; padding: 0; font-size: 11.5px; }
.tt-node.is-cancel { border-color: var(--oxblood); background: color-mix(in srgb, var(--oxblood) 10%, var(--surface)); }

/* ---------- Topic 11 labs ---------- */
.mb { display: grid; gap: 8px; margin: 12px 0; overflow-x: auto; }
.mb-lane { display: flex; align-items: center; gap: 10px; }
.mb-lane > b { min-width: 34px; font: 700 11px var(--font-mono); color: var(--muted); }
.mb-track { position: relative; height: 34px; border-bottom: 1.5px solid var(--line); flex: none; }
.mb-dot { position: absolute; top: 2px; min-width: 26px; height: 26px; padding: 0 5px; border-radius: 13px; display: grid; place-items: center; font: 700 11px var(--font-mono); border: 1.5px solid; background: var(--surface); transition: left .3s; }
.mb-dot.is-a { border-color: var(--green); color: var(--green); }
.mb-dot.is-b { border-color: var(--brass); color: var(--ink); }
.mb-dot.is-out { border-color: var(--plum); background: color-mix(in srgb, var(--plum) 14%, var(--surface)); }
.dm { display: flex; flex-wrap: wrap; gap: 6px; margin: 12px 0; }
.dm-item { padding: 8px 14px; border-radius: 10px; border: 1.5px solid var(--line); font: 700 12px var(--font-mono); transition: all .3s; }
.dm-item.is-got { border-color: var(--leaf); background: color-mix(in srgb, var(--leaf) 14%, var(--surface)); }
.dm-item.is-wait { opacity: .45; border-style: dashed; }

/* ---------- Topic 12 labs ---------- */
.bo { display: grid; gap: 4px; margin: 12px 0; overflow-x: auto; }
.bo-row { display: flex; align-items: center; gap: 8px; }
.bo-row > b { min-width: 26px; font: 700 10.5px var(--font-mono); color: var(--muted); }
.bo-track { position: relative; width: 530px; height: 18px; border-bottom: 1px dashed var(--line); flex: none; }
.bo-track i { position: absolute; top: 3px; width: 10px; height: 10px; margin-left: -5px; border-radius: 50%; background: var(--oxblood); transition: left .35s; }

/* ---------- Topic 13 labs ---------- */
.sv { display: grid; gap: 6px; margin: 12px 0; }
.sv-row { display: grid; grid-template-columns: minmax(150px, 1.2fr) 80px 2fr; gap: 10px; align-items: baseline; padding: 8px 12px; border-radius: 10px; border: 1.5px solid var(--line); background: var(--surface); transition: background .3s, border-color .3s; }
.sv-row b { font-size: 13px; }
.sv-row i { font-size: 12px; color: var(--muted); font-style: normal; }
.sv-mark { font: 800 11px var(--font-mono); text-transform: uppercase; letter-spacing: .05em; }
.sv-row.is-yes { border-color: color-mix(in srgb, var(--leaf) 45%, var(--line)); background: color-mix(in srgb, var(--leaf) 10%, var(--surface)); }
.sv-row.is-yes .sv-mark { color: var(--leaf); }
.sv-row.is-no { border-color: var(--oxblood); background: color-mix(in srgb, var(--oxblood) 9%, var(--surface)); }
.sv-row.is-no .sv-mark { color: var(--oxblood); }
.sv-row.is-maybe { border-color: var(--brass); background: color-mix(in srgb, var(--brass) 14%, var(--surface)); }
@media (max-width: 560px) { .sv-row { grid-template-columns: 1fr; gap: 2px; } }

/* ---------- Topic 14 labs ---------- */
.dl-list { display: grid; gap: 5px; margin: 12px 0; }
.dl-list .btn { text-align: left; justify-content: flex-start; font-size: 11.5px; overflow-wrap: anywhere; }

/* ---------- Topic 16 labs ---------- */
.gl { display: grid; gap: 8px; margin: 12px 0; }
.gl-row { display: flex; flex-wrap: wrap; justify-content: center; gap: 8px; }
.gl-node { display: flex; flex-direction: column; gap: 1px; min-width: 120px; padding: 8px 12px; border-radius: 10px; border: 1.5px solid var(--line); background: var(--surface); text-align: left; cursor: pointer; font: inherit; color: var(--ink); transition: background .3s, border-color .3s; }
.gl-node b { font-size: 12.5px; }
.gl-node span { font: 600 10px var(--font-mono); color: var(--muted); }
.gl-node.is-aff { border-color: var(--brass); background: color-mix(in srgb, var(--brass) 16%, var(--surface)); }
.gl-node.is-changed { border-color: var(--oxblood); background: color-mix(in srgb, var(--oxblood) 12%, var(--surface)); }
.gl-bar { height: 10px; border-radius: 6px; background: var(--surface-2); margin: 12px 0; overflow: hidden; }
.gl-bar > div { height: 100%; background: var(--green); transition: width .3s; }

/* ---------- Topic 19 labs ---------- */
.tl-bar { display: grid; grid-template-columns: repeat(24, 1fr); gap: 2px; margin: 12px 0; max-width: 480px; }
.tl-bar i { height: 22px; border-radius: 3px; background: var(--surface-2); border: 1px solid var(--line); }
.tl-bar i.is-ok { background: color-mix(in srgb, var(--leaf) 45%, transparent); border-color: var(--leaf); }
.tl-bar i.is-stale { background: color-mix(in srgb, var(--oxblood) 18%, transparent); border-color: var(--oxblood); }

/* ---------- Topic 20 labs ---------- */
.fc-grid { display: grid; grid-template-columns: repeat(3, 76px); gap: 8px; margin: 12px 0; }
.fc-cell { height: 56px; border-radius: 10px; border: 1.5px dashed var(--line); display: grid; place-items: center; font-size: 11px; color: var(--muted); transition: all .25s; }
.fc-cell.is-item { border-style: solid; background: var(--surface); color: var(--ink); }
.fc-cell.is-focus { border-color: var(--green); background: color-mix(in srgb, var(--green) 18%, var(--surface)); transform: scale(1.08); box-shadow: 0 6px 16px rgba(0,0,0,.25); }
.fc-cell.is-guide { border-color: var(--brass); background: color-mix(in srgb, var(--brass) 14%, transparent); }
.aod-face { display: flex; flex-direction: column; gap: 4px; align-items: center; justify-content: center; width: 180px; height: 150px; border-radius: 36px; background: #0a0a0a; color: #f2f2f2; border: 2px solid var(--line); margin: 12px 0; transition: all .3s; }
.aod-face b { font: 700 28px var(--font-mono); }
.aod-face span { font-size: 11px; opacity: .9; }
.aod-face.is-dim { color: #6a6a6a; }

/* ---------- Topic 21 labs ---------- */
.pl-chart { display: flex; align-items: flex-end; gap: 4px; height: 80px; margin: 12px 0; }
.pl-bar { display: block; width: 14px; border-radius: 3px 3px 0 0; background: var(--green); }
.pl-bar.is-slow { background: var(--oxblood); }
.rl-strip { display: grid; grid-template-columns: repeat(60, 1fr); gap: 1px; margin: 12px 0; max-width: 480px; }
.rl-sec { height: 22px; background: var(--line); border-radius: 1px; }
.rl-sec.is-on { background: color-mix(in srgb, var(--brass) 55%, var(--surface)); }
.rl-sec.is-req { background: var(--oxblood); }
.th-bars { display: grid; gap: 6px; margin: 12px 0; max-width: 520px; }
.th-row { display: grid; grid-template-columns: minmax(120px, 1.2fr) 2fr auto; gap: 8px; align-items: center; font-size: 12px; }
.th-row i { display: block; height: 10px; border-radius: 5px; background: var(--brass); }
.th-row b { font-variant-numeric: tabular-nums; }

/* ---------- Topic 22 labs ---------- */
.pyr { display: grid; gap: 6px; margin: 12px 0; max-width: 520px; }
.pyr-row { display: grid; grid-template-columns: 90px 1fr 44px; gap: 8px; align-items: center; font-size: 12px; }
.pyr-row i { display: block; height: 12px; border-radius: 6px; background: var(--green); }
.pyr-row b { font-variant-numeric: tabular-nums; text-align: right; }

/* ---------- Topic 24 labs ---------- */
.vo-card { display: flex; align-items: center; gap: 12px; padding: 10px 14px; border: 1.5px solid var(--line); border-radius: 12px; max-width: 320px; margin: 12px 0; background: var(--surface); }
.vo-card b { flex: 1; }
.dt-row { display: flex; gap: 12px; align-items: flex-start; border: 1.5px solid var(--line); border-radius: 12px; padding: 12px; margin: 12px 0; max-width: 520px; background: var(--surface); }
.dt-row i { display: block; flex: none; border-radius: 50%; background: var(--green); }
.dt-row.is-stack { flex-direction: column; }
.ct-sample { display: grid; gap: 4px; padding: 14px 16px; border-radius: 12px; margin: 12px 0; max-width: 420px; border: 1.5px solid var(--line); }
.ct-sample b { font-size: 22px; }
.rtl-row { display: flex; align-items: center; gap: 12px; padding: 10px 14px; border: 1.5px solid var(--line); border-radius: 12px; max-width: 360px; margin: 12px 0; background: var(--surface); }
.rtl-row .grow { flex: 1; }
.rtl-row .flip { font-size: 22px; }
[dir="rtl"] .rtl-row .flip, .rtl-row[dir="rtl"] .flip { transform: scaleX(-1); display: inline-block; }
.rtl-box { position: relative; width: 200px; height: 52px; border: 1.5px dashed var(--line); border-radius: 8px; margin: 12px 0; }
.rtl-box i { position: absolute; width: 50px; height: 20px; font: 10px/20px var(--font-mono); text-align: center; border-radius: 4px; font-style: normal; white-space: nowrap; overflow: hidden; }
.rtl-box .lead { top: 4px; background: var(--green); color: #fff; }
.rtl-box .left { top: 28px; background: var(--brass); color: #fff; }

/* long inline code in answers and long words in labs must wrap on narrow screens */
p code, li code { white-space: normal; overflow-wrap: anywhere; }
.dt-row span { overflow-wrap: anywhere; min-width: 0; }

/* ---------- Topic 25 labs ---------- */
.ro-strip { display: grid; grid-template-columns: repeat(7, 1fr); gap: 4px; max-width: 460px; margin: 12px 0; }
.ro-day { display: block; font-style: normal; text-align: center; padding: 10px 0; border-radius: 8px; border: 1.5px solid var(--line); font-size: 12px; }
.ro-day.is-on { background: color-mix(in srgb, var(--green) 22%, var(--surface)); border-color: var(--green); }
.ro-day.is-pause { background: color-mix(in srgb, var(--oxblood) 20%, var(--surface)); border-color: var(--oxblood); }
.vl-in { font: 13px var(--font-mono); padding: 4px 8px; border: 1.5px solid var(--line); border-radius: 8px; background: var(--surface); color: var(--ink); width: 110px; max-width: 100%; }
.vl-code { font: 12px var(--font-mono); padding: 8px 12px; border: 1.5px solid var(--line); border-radius: 8px; background: var(--surface); margin: 8px 0; white-space: pre-wrap; overflow-wrap: anywhere; }
.bk-grid { display: grid; grid-template-columns: repeat(20, 1fr); gap: 3px; max-width: 420px; margin: 12px 0; }
.bk-cell { display: block; aspect-ratio: 1; border-radius: 3px; background: var(--line); }
.bk-cell.is-on { background: var(--green); }

/* ---------- Topic 26 labs ---------- */
.dm-row { display: grid; grid-template-columns: minmax(120px, 1.2fr) 2fr 20px; gap: 8px; align-items: center; font-size: 12px; max-width: 520px; width: 100%; }
.dm-row b { font-variant-numeric: tabular-nums; text-align: right; }

/* long unbroken option text (URLs, hashes) must wrap inside the card */
.pick { max-width: 100%; min-width: 0; overflow-wrap: anywhere; text-align: left; }

/* ---------- topic list in the sidebar ---------- */
.nav-topics { gap: 1px; }
.nav-topic { padding: 7px 12px; font-size: 13.2px; }
.nav-topic.is-current { background: var(--surface); color: var(--ink); font-weight: 700; box-shadow: var(--shadow-sm); }
.nav-topic.is-current .nav-num { color: var(--green); }
.nav-sub { margin: 3px 0 8px 14px; padding-left: 8px; border-left: 2px solid var(--line); }
.nav-sec { padding: 6px 10px; font-size: 12.8px; }

/* ---------- home: no sidebar; topic picker inside topics ---------- */
body.no-sidebar .layout { grid-template-columns: minmax(0, 1480px); }
body.no-sidebar .sidebar, body.no-sidebar .menu-btn { display: none !important; }
.topic-pick { margin: 0 0 18px; }
.topic-pick summary { display: flex; align-items: center; gap: 10px; cursor: pointer; list-style: none; padding: 9px 12px; border-radius: 11px; background: var(--surface); box-shadow: var(--shadow-sm); font-weight: 700; font-size: 13.6px; }
.topic-pick summary::-webkit-details-marker { display: none; }
.topic-pick summary::after { content: '▾'; margin-left: auto; color: var(--muted); }
.topic-pick[open] summary::after { content: '▴'; }
.topic-pick .nav-list { margin: 8px 0 0; max-height: 50vh; overflow-y: auto; }
.topic-pick .nav-link { padding: 6px 12px; font-size: 13px; }

/* ---------- next-step call to action ---------- */
.next-cta { display: grid; gap: 10px; margin: 34px 0 6px; }
.next-card { position: relative; display: grid; gap: 4px; padding: 18px 56px 18px 20px; border-radius: 16px; background: var(--surface); border: 1.5px solid var(--line-strong); box-shadow: var(--shadow-sm); color: var(--ink); text-decoration: none; transition: transform .16s var(--ease-out, ease), border-color .16s, box-shadow .16s; }
.next-card:hover { transform: translateY(-2px); border-color: var(--green); box-shadow: var(--shadow-md, var(--shadow-sm)); }
.next-kicker { font-family: var(--font-round); font-size: 11.5px; font-weight: 700; letter-spacing: .09em; text-transform: uppercase; color: var(--green); }
.next-card strong { font-size: 17px; line-height: 1.3; overflow-wrap: anywhere; }
.next-note { font-size: 13.5px; color: var(--ink-2); line-height: 1.45; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }
.next-arrow { position: absolute; right: 20px; top: 50%; transform: translateY(-50%); font-size: 22px; color: var(--green); }
.next-prev { justify-self: start; font-size: 13px; color: var(--muted); text-decoration: none; padding: 4px 2px; overflow-wrap: anywhere; }
.next-prev:hover { color: var(--ink); }

/* ---------- revise deck: star button + topbar entry ---------- */
.star-btn {
  display: inline-flex; align-items: center; gap: 5px;
  font: inherit; font-size: 12px; font-weight: 600; color: var(--ink-2);
  background: var(--surface); border: 1px solid var(--line-strong); border-radius: 999px;
  padding: 3px 11px; min-height: 28px; cursor: pointer;
  transition: background .15s, border-color .15s, color .15s, transform .15s;
}
.star-btn:hover { border-color: var(--brass); color: var(--ink); transform: translateY(-1px); }
.star-btn.is-on { background: color-mix(in srgb, var(--brass) 18%, var(--surface)); border-color: var(--brass); color: var(--ink); }
.star-btn.is-on > span:first-child { color: var(--brass); }
.star-btn:focus-visible, .revise-btn:focus-visible { outline: 2px solid var(--brass); outline-offset: 2px; }
.qbank + .star-btn { margin-left: 0; }
.revise-btn {
  display: inline-flex; align-items: center; gap: 6px; height: 38px; padding: 0 13px;
  font: inherit; font-size: 13px; font-weight: 600; color: var(--ink-2);
  background: var(--surface); border: 1px solid var(--line); border-radius: 999px; cursor: pointer;
  white-space: nowrap; transition: transform .15s, border-color .15s, color .15s;
}
.revise-btn:hover { transform: translateY(-1px); border-color: var(--line-strong); color: var(--ink); }
.revise-btn b { font-family: var(--font-mono); font-size: 11.5px; min-width: 20px; text-align: center; padding: 1px 6px; border-radius: 999px; background: var(--line); color: var(--ink-2); }
.revise-btn.has-cards > span:first-child { color: var(--brass); }
.revise-btn.has-cards b { background: var(--brass); color: #1b1608; }
@media (max-width: 640px) {
  .revise-text { display: none; }
  .revise-btn { padding: 0 10px; }
  .star-btn { min-height: 36px; padding: 4px 12px; }
}

/* ---------- quiz hub ---------- */
.hub-h { font-family: var(--font-display); font-size: 19px; margin: 26px 0 12px; }
.hub-h-sub { font-size: 14px; font-family: var(--font-body, inherit); color: var(--muted); font-weight: 600; margin: 18px 0 10px; }
.hub-quick { display: grid; grid-template-columns: repeat(auto-fill, minmax(200px, 1fr)); gap: 10px; }
.hub-topics { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 10px; }
.hub-opt, .hub-topic {
  position: relative; text-align: left; font: inherit; color: inherit; cursor: pointer;
  background: var(--surface); border: 1px solid var(--line); border-radius: 14px; padding: 12px 14px;
  display: grid; gap: 3px; transition: border-color .15s, transform .15s, background .15s;
}
.hub-opt:hover:not(:disabled), .hub-topic:hover { border-color: var(--line-strong); transform: translateY(-1px); }
.hub-opt:disabled { opacity: .45; cursor: not-allowed; }
.hub-opt b { font-size: 14px; }
.hub-opt span { font-size: 12px; color: var(--muted); }
.hub-opt i { position: absolute; top: 10px; right: 12px; font-style: normal; font-family: var(--font-mono); font-size: 12px; color: var(--ink-2); }
.hub-opt.is-on, .hub-topic.is-on { border-color: var(--brass); background: color-mix(in srgb, var(--brass) 12%, var(--surface)); box-shadow: 0 0 0 1px var(--brass) inset; }
.hub-topic { grid-template-columns: auto 1fr; column-gap: 10px; align-items: baseline; border-left: 3px solid var(--accent, var(--green)); }
.ht-num { font-family: var(--font-mono); font-size: 11.5px; color: var(--muted); }
.ht-title { font-size: 13.5px; font-weight: 600; line-height: 1.3; }
.ht-meta { grid-column: 2; font-size: 11.5px; color: var(--muted); }
.ht-bar { grid-column: 1 / -1; height: 3px; border-radius: 3px; background: var(--line); overflow: hidden; margin-top: 4px; }
.ht-bar i { display: block; height: 100%; background: var(--accent, var(--green)); }
.hub-row { display: flex; align-items: center; gap: 14px; flex-wrap: wrap; margin: 8px 0; }
.hub-k { width: 92px; font-size: 12.5px; font-weight: 600; color: var(--muted); }
.hub-chips { display: flex; gap: 7px; flex-wrap: wrap; }
.hub-start {
  position: sticky; bottom: 12px; margin-top: 26px; z-index: 5;
  display: flex; align-items: center; justify-content: space-between; gap: 14px; flex-wrap: wrap;
  background: var(--surface); border: 1px solid var(--line-strong); border-radius: 16px; padding: 12px 16px;
  box-shadow: var(--shadow-lift);
}
.hub-start > div { display: grid; gap: 1px; min-width: 0; }
.hub-start b { font-size: 14px; overflow-wrap: anywhere; }
.hub-start span { font-size: 12px; color: var(--muted); }
.hero-cta { margin-top: 18px; }
@media (max-width: 640px) {
  .hub-k { width: 100%; }
  .hub-start .btn { flex: 1 1 100%; }
}

.hub-choose { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 16px; margin-top: 8px; }
.hub-big {
  display: grid; gap: 8px; align-content: start; padding: 22px;
  background: var(--surface); border: 1px solid var(--line); border-radius: 18px; box-shadow: var(--shadow-sm);
}
.hub-big h2 { font-family: var(--font-display); font-size: 22px; margin: 0; }
.hub-big p { margin: 0 0 8px; color: var(--ink-2); font-size: 14.5px; line-height: 1.5; }
.hub-big .btn { justify-self: start; }
.hb-kicker { font-size: 12px; font-weight: 700; letter-spacing: .4px; text-transform: uppercase; color: var(--muted); }
.hub-revise { border-color: var(--brass); background: color-mix(in srgb, var(--brass) 9%, var(--surface)); }
.hub-revise .hb-kicker { color: var(--brass); }
.hub-revise.is-empty { border-color: var(--line); background: var(--surface); }
.hub-back { background: none; border: 0; font: inherit; cursor: pointer; padding: 0; }

/* ---------- newsletter signup ---------- */
.nl { display: grid; gap: 8px; background: var(--surface); border: 1px solid var(--line); border-radius: 16px; padding: 18px 20px; }
.nl-home { margin: 36px 0 8px; }
.nl-prompt { margin: 22px auto; max-width: 520px; text-align: left; }
.nl-footer { max-width: 520px; margin: 0 auto 14px; background: none; border-style: dashed; padding: 14px 16px; }
.nl-copy { display: grid; gap: 2px; }
.nl-copy b { font-size: 14.5px; }
.nl-copy span, .nl-fine { font-size: 12.5px; color: var(--muted); margin: 0; }
.nl-row { display: flex; gap: 8px; flex-wrap: wrap; align-items: center; }
.nl-row input[type="email"] {
  flex: 1 1 200px; min-width: 0; font: inherit; font-size: 14px; color: var(--ink);
  background: var(--surface-2); border: 1px solid var(--line-strong); border-radius: 10px; padding: 9px 12px;
}
.nl-row input[type="email"]:focus-visible { outline: 2px solid var(--brass); outline-offset: 1px; }
.nl-hp { position: absolute; left: -9999px; width: 1px; height: 1px; opacity: 0; }
.nl-dismiss { background: none; border: 0; font: inherit; font-size: 12.5px; color: var(--muted); cursor: pointer; text-decoration: underline; padding: 6px; }
.nl-msg { margin: 0; min-height: 1em; font-size: 12.5px; color: var(--ink-2); }
.nl-msg.is-bad { color: var(--oxblood); }
.nl-done { padding: 14px 18px; font-size: 14px; }
body.no-sidebar .nl-footer { display: none; }

/* ---------- footer links + credit ---------- */
.foot-links { display: flex; gap: 8px; flex-wrap: wrap; justify-content: center; margin: 0 auto 12px; }
.foot-link {
  font-size: 12.5px; font-weight: 600; color: var(--ink-2); text-decoration: none;
  border: 1px solid var(--line-strong); border-radius: 999px; padding: 6px 13px; background: var(--surface);
  transition: border-color .15s, color .15s, transform .15s;
}
.foot-link:hover { border-color: var(--brass); color: var(--ink); transform: translateY(-1px); }
.foot-link:focus-visible { outline: 2px solid var(--brass); outline-offset: 2px; }
.foot-topmate { border-color: var(--brass); color: var(--ink); }
.foot-credit { margin: 8px 0 0; font-size: 12.5px; color: var(--muted); text-align: center; }
.heart { color: #c9344a; }
[data-theme="dark"] .heart { color: #ff7a8a; }
.site-foot .foot-credit { text-align: center; }

/* ---------- feedback ---------- */
.card-foot { margin-top: 14px; padding-top: 10px; border-top: 1px dashed var(--line); }
.fb-link { background: none; border: 0; font: inherit; font-size: 12.5px; color: var(--muted); cursor: pointer; padding: 4px 0; text-decoration: underline; text-underline-offset: 3px; text-align: left; }
.fb-link:hover { color: var(--ink); }
button.foot-link { font: inherit; font-size: 12.5px; font-weight: 600; cursor: pointer; }
.fb-dialog { border: 1px solid var(--line-strong); border-radius: 18px; padding: 0; background: var(--surface); color: var(--ink); width: min(520px, calc(100vw - 28px)); box-shadow: var(--shadow-lift); }
.fb-dialog::backdrop { background: rgba(8, 12, 10, .55); }
.fb-form { display: grid; gap: 12px; padding: 20px; }
.fb-head { display: flex; align-items: center; justify-content: space-between; }
.fb-head h2 { margin: 0; font-family: var(--font-display); font-size: 20px; }
.fb-x { background: none; border: 0; font-size: 24px; line-height: 1; color: var(--muted); cursor: pointer; padding: 2px 8px; }
.fb-ctx { margin: 0; font-size: 12.5px; color: var(--muted); overflow-wrap: anywhere; }
.fb-ctx b { color: var(--ink-2); font-weight: 600; }
.fb-field { display: grid; gap: 5px; font-size: 12.5px; font-weight: 600; color: var(--ink-2); }
.fb-field select, .fb-field textarea, .fb-field input {
  font: inherit; font-size: 14px; font-weight: 400; color: var(--ink); background: var(--surface-2);
  border: 1px solid var(--line-strong); border-radius: 10px; padding: 9px 12px; width: 100%; box-sizing: border-box;
}
.fb-field textarea { resize: vertical; min-height: 110px; }
.fb-field :focus-visible, .fb-x:focus-visible { outline: 2px solid var(--brass); outline-offset: 1px; }
.fb-extra { display: grid; gap: 12px; }
.fb-extra[hidden] { display: none; }
.fb-note { margin: 0; font-size: 12px; color: var(--muted); }
.fb-actions { display: flex; gap: 10px; justify-content: flex-end; flex-wrap: wrap; }
.fb-actions .btn { min-height: 40px; }

.fb-top {
  display: inline-flex; align-items: center; gap: 5px; font: inherit; font-size: 12px; font-weight: 600;
  color: var(--ink-2); background: none; border: 1px solid var(--line-strong); border-radius: 999px;
  padding: 3px 11px; min-height: 28px; cursor: pointer; transition: border-color .15s, color .15s;
}
.fb-top:hover { border-color: var(--brass); color: var(--ink); }
.fb-top:focus-visible { outline: 2px solid var(--brass); outline-offset: 2px; }
@media (max-width: 640px) { .fb-top { min-height: 36px; padding: 4px 12px; } }

/* ---------- company chips: brand-coloured, logo or letter badge ---------- */
.qco { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; margin: -2px 0 12px; }
.qco-label { font-size: 11.5px; font-weight: 600; letter-spacing: .3px; text-transform: uppercase; color: var(--muted); }
.co {
  --mark: color-mix(in srgb, var(--brand) 72%, var(--ink));       /* keeps the hue but stays readable on both themes */
  display: inline-flex; align-items: center; gap: 7px; font-size: 12.5px; font-weight: 700; color: var(--ink);
  background: color-mix(in srgb, var(--brand) 16%, var(--surface-2));
  border: 1px solid color-mix(in srgb, var(--brand) 55%, transparent);
  border-radius: 999px; padding: 3px 11px 3px 4px; cursor: help;
}
.co i {
  display: grid; place-items: center; width: 20px; height: 20px; border-radius: 50%; font-style: normal; font-size: 11px; font-weight: 700;
  color: var(--mark-fg, #fff); background: var(--mark-bg, var(--brand));
}
.co i.co-logo {
  background: var(--mark); color: inherit; border-radius: 0;
  -webkit-mask: var(--logo) center / 15px 15px no-repeat; mask: var(--logo) center / 15px 15px no-repeat;
}

@media (max-width: 640px) { .revise-btn { height: 34px; padding: 0 8px; gap: 4px; } }

/* ---------- top-bar calls to action: Feedback (yellow) and Revise (green) ---------- */
:root { --on-green: #fff; }
[data-theme="dark"] { --on-green: #08150f; }
#feedback-btn {
  background: var(--brass-bright); border-color: var(--brass-bright); color: var(--on-brass);
  box-shadow: 0 6px 16px -8px color-mix(in srgb, var(--brass-bright) 80%, transparent);
}
#feedback-btn:hover { background: color-mix(in srgb, var(--brass-bright) 88%, #000); border-color: transparent; color: var(--on-brass); }
[data-theme="dark"] #feedback-btn:hover { background: color-mix(in srgb, var(--brass-bright) 86%, #fff); }
#revise-btn {
  background: var(--green); border-color: var(--green); color: var(--on-green);
  box-shadow: 0 6px 16px -8px color-mix(in srgb, var(--green) 80%, transparent);
}
#revise-btn:hover { background: color-mix(in srgb, var(--green) 88%, #000); border-color: transparent; color: var(--on-green); }
[data-theme="dark"] #revise-btn:hover { background: color-mix(in srgb, var(--green) 86%, #fff); }
#revise-btn b { background: color-mix(in srgb, var(--on-green) 14%, transparent); color: var(--on-green); }
#revise-btn.has-cards > span:first-child { color: inherit; }
#revise-btn.has-cards b { background: var(--on-green); color: var(--green); }
#feedback-btn:focus-visible, #revise-btn:focus-visible { outline: 2px solid var(--ink); outline-offset: 2px; }

.quiz-nav { display: flex; justify-content: space-between; gap: 10px; margin-top: 14px; }
.quiz-nav .btn { min-height: 42px; }
.quiz-nav .btn:last-child { margin-left: auto; }
@media (max-width: 640px) { .quiz-nav .btn { flex: 1 1 0; } }

/* ---------- quiz round sidebar ---------- */
.round-list { max-height: 52vh; overflow-y: auto; padding-right: 4px; display: grid; grid-template-columns: minmax(0, 1fr); }
.round-list li { min-width: 0; }
.round-link { width: 100%; background: none; border: 0; font: inherit; text-align: left; cursor: pointer; color: inherit; align-items: flex-start; }
.round-title {
  flex: 1; min-width: 0; font-size: 12.5px; line-height: 1.35;
  display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden;
}
.round-mark { width: 16px; flex: none; text-align: center; font-size: 12px; font-weight: 700; color: var(--muted); }
.round-mark.is-got { color: var(--leaf); }
.round-mark.is-shaky { color: var(--brass); }
.round-mark.is-missed { color: var(--oxblood); }

/* the Next / Previous bar stays in view while you read a long answer */
.quiz-nav {
  position: sticky; bottom: 12px; z-index: 6; padding: 8px;
  background: color-mix(in srgb, var(--surface) 88%, transparent);
  backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px);
  border: 1px solid var(--line); border-radius: 16px; box-shadow: var(--shadow-lift);
}
.quiz-nav .quiz-next { padding-inline: 24px; font-weight: 700; }
.quiz-nav .quiz-next.is-hot { animation: nextPulse 1.8s ease-in-out 2; }
@keyframes nextPulse {
  0%, 100% { box-shadow: 0 6px 16px -8px color-mix(in srgb, var(--brass-bright) 80%, transparent); }
  50% { box-shadow: 0 0 0 6px color-mix(in srgb, var(--brass-bright) 35%, transparent); }
}
@media (prefers-reduced-motion: reduce) { .quiz-nav .quiz-next.is-hot { animation: none; } }

/* Previous: clearly visible, but a step below the yellow Next */
.quiz-nav [data-prev] {
  background: color-mix(in srgb, var(--green) 16%, var(--surface));
  border: 1.5px solid var(--green); color: var(--ink); font-weight: 700; padding-inline: 20px;
}
.quiz-nav [data-prev]:hover:not(:disabled) { background: color-mix(in srgb, var(--green) 26%, var(--surface)); border-color: var(--green); color: var(--ink); }
.quiz-nav [data-prev]:disabled { background: transparent; border: 1px solid var(--line); color: var(--muted); font-weight: 600; opacity: .6; }
.quiz-nav [data-prev]:focus-visible { outline: 2px solid var(--ink); outline-offset: 2px; }

/* Next is always solid yellow; it pulses once the answer is shown */
.quiz-nav .quiz-next:focus-visible { outline: 2px solid var(--ink); outline-offset: 2px; }


/* ---------- review fixes ---------- */
.search-more { text-align: center; padding: 24px 0 8px; color: var(--muted); }
.search-more p { margin: 0 0 10px; font-size: 13px; }
.skip-link {
  position: absolute; left: 12px; top: -48px; z-index: 100;
  background: var(--brass-bright); color: var(--on-brass); padding: 10px 14px; border-radius: 10px; font-weight: 700;
  text-decoration: none; transition: top .15s;
}
.skip-link:focus { top: 10px; }
:focus-visible { outline: 2px solid var(--brass-bright); outline-offset: 2px; }
.qhint-rate[hidden] { display: none; }
[data-theme="dark"] .rate-btn.is-picked[data-rate="missed"] { background: color-mix(in srgb, var(--oxblood) 38%, var(--surface)); box-shadow: 0 0 0 2px var(--oxblood); }
[data-theme="dark"] .rate-btn.is-picked[data-rate="shaky"]  { background: color-mix(in srgb, var(--brass) 34%, var(--surface)); box-shadow: 0 0 0 2px var(--brass); }
[data-theme="dark"] .rate-btn.is-picked[data-rate="got"]    { background: color-mix(in srgb, var(--leaf) 34%, var(--surface)); box-shadow: 0 0 0 2px var(--leaf); }
.btn:disabled { opacity: .5; cursor: not-allowed; }
#feedback-btn[hidden], .fb-top[hidden] { display: none !important; }

/* ---------- company browsing ---------- */
a.co { text-decoration: none; cursor: pointer; }
a.co:hover { border-color: var(--brand); background: color-mix(in srgb, var(--brand) 26%, var(--surface-2)); }
.co-pick b { font-size: 11px; font-weight: 700; color: var(--muted); }
.co-strip { display: flex; flex-wrap: wrap; gap: 8px; margin: 0 0 8px; }
.home-h { font-family: var(--font-display); font-size: 22px; margin: 28px 0 4px; }
.home-sub { margin: 0 0 12px; font-size: 13px; color: var(--muted); }

/* hidden round titles, focus target for route changes */
.round-hidden { background: repeating-linear-gradient(90deg, var(--line-strong) 0 6px, transparent 6px 9px); height: 2px; align-self: center; border-radius: 2px; opacity: .8; }
#view:focus { outline: none; }
#view:focus-visible { outline: 2px solid var(--brass-bright); outline-offset: 2px; }
body.is-loading, body.is-loading * { cursor: progress; }

/* Topic 16 labs: uses shared lab classes only. */