/* =====================================================================
   Hardcore Go - Interactive Course · Design System
   ===================================================================== */

/* ----------------------------------------------------------- tokens */
:root {
  --go: #00add8;
  --go-soft: #5dc9e2;
  --go-deep: #0090b4;
  --purple: #a98bff;
  --accent: #ec4a7d;
  --good: #3ad29f;
  --warn: #f5b14c;
  --bad: #ff6b6b;

  --radius: 10px;
  --radius-sm: 7px;
  --maxw: 1080px;
  --ease: cubic-bezier(.22, .61, .36, 1);
  --ease-pop: cubic-bezier(.34, 1.56, .64, 1);
  --font: "Inter", system-ui, -apple-system, sans-serif;
  --font-serif: Georgia, "Times New Roman", serif;
  --mono: "JetBrains Mono", ui-monospace, "SF Mono", monospace;
}

/* dark (default) */
:root[data-theme="dark"] {
  --bg: #0d1117;
  --bg-2: #10141a;
  --surface: #161b22;
  --surface-2: #1b2129;
  --surface-3: #20272f;
  --border: #2d343c;
  --border-soft: #21272e;
  --text: #e6e8eb;
  --text-2: #9aa1ab;
  --text-3: #6c7280;
  --shadow: 0 10px 30px -16px rgba(0, 0, 0, .55);
  --glow: 0 0 0 1px var(--border);

  --anim-bg: #0d1117;
  --anim-panel: #161b22;
  --anim-line: #2d343c;
  --anim-text: #d7dade;
  --anim-dim: #6c7280;

  --t-com: #6b7280;
  --t-str: #7fd6a8;
  --t-num: #f0a96b;
  --t-kw: #6cb6ff;
  --t-bi: #c89bff;
  --t-fn: #5dc9e2;
}

/* light */
:root[data-theme="light"] {
  --bg: #faf8f4;
  --bg-2: #f4f1ea;
  --surface: #ffffff;
  --surface-2: #f6f3ec;
  --surface-3: #efeae0;
  --border: #e1dbcc;
  --border-soft: #ebe6d9;
  --text: #201d18;
  --text-2: #403b31;
  --text-3: #5d5749;
  --shadow: 0 8px 24px -16px rgba(30, 25, 15, .25);
  --glow: 0 0 0 1px var(--border);

  --anim-bg: #ffffff;
  --anim-panel: #f6f3ec;
  --anim-line: #e1dbcc;
  --anim-text: #201d18;
  --anim-dim: #837c68;

  --t-com: #93a3b8;
  --t-str: #1a925e;
  --t-num: #c2570f;
  --t-kw: #1f6fd6;
  --t-bi: #8a4bd6;
  --t-fn: #0090b4;
}

* { box-sizing: border-box; }
html, body { height: 100%; margin: 0; }
body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
  line-height: 1.6;
  overflow-x: hidden;
}
a { color: inherit; text-decoration: none; }
::selection { background: color-mix(in srgb, var(--go) 22%, transparent); }
.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;
}

/* scrollbars */
*::-webkit-scrollbar { width: 10px; height: 10px; }
*::-webkit-scrollbar-thumb { background: var(--border); border-radius: 8px; }
*::-webkit-scrollbar-thumb:hover { background: var(--text-3); }

/* ----------------------------------------------------------- layout */
#app { min-height: 100%; display: flex; flex-direction: column; }

.topbar {
  position: sticky; top: 0; z-index: 40;
  display: flex; align-items: center; gap: 14px;
  padding: 12px 22px;
  background: var(--bg-2);
  border-bottom: 1px solid var(--border-soft);
}
.brand { display: flex; align-items: center; gap: 11px; min-width: 0; }
.brand-mark {
  font: 700 16px var(--mono);
  background: var(--go);
  color: #04121c; width: 34px; height: 34px;
  display: grid; place-items: center; border-radius: 8px;
}
.brand-text { display: flex; flex-direction: column; line-height: 1.1; min-width: 0; }
.brand-text b { font: 700 14.5px var(--font-serif); letter-spacing: 0; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.brand-text small { font-size: 10.5px; color: var(--text-3); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.topbar-right { margin-left: auto; display: flex; align-items: center; gap: 16px; }
.top-progress { display: flex; align-items: center; gap: 9px; }
.tp-bar { width: 120px; height: 6px; border-radius: 6px; background: var(--surface-3); overflow: hidden; }
.tp-bar > span { display: block; height: 100%; border-radius: 6px;
  background: var(--go); transition: width .5s var(--ease); }
.tp-num { font: 600 12px var(--mono); color: var(--text-2); min-width: 34px; }
.icon-btn { background: var(--surface-2); border: 1px solid var(--border); color: var(--text);
  width: 36px; height: 36px; border-radius: 8px; cursor: pointer; font-size: 16px;
  display: grid; place-items: center;
  transition: transform .2s var(--ease-pop), border-color .2s, color .2s; }
.icon-btn:hover { border-color: var(--go); color: var(--go); transform: scale(1.08) rotate(-6deg); }
.icon-btn:active { transform: scale(.92); }
.lang-btn { width: 40px; font: 700 11px var(--mono); letter-spacing: .3px; }
.nav-toggle { display: none; background: none; border: none; color: var(--text); font-size: 22px; cursor: pointer; place-items: center; }

.layout { flex: 1; display: grid; grid-template-columns: 290px minmax(0, 1fr); align-items: start; min-width: 0; }

/* ----------------------------------------------------------- sidebar */
.sidebar {
  position: sticky; top: 59px; align-self: start;
  height: calc(100vh - 59px);
  border-right: 1px solid var(--border-soft);
  background: var(--bg-2);
  display: flex; flex-direction: column;
  overflow: hidden;
}
.nav-search { padding: 14px 14px 6px; }
.nav-search input {
  width: 100%; padding: 9px 12px; border-radius: 8px;
  background: var(--surface); border: 1px solid var(--border); color: var(--text);
  font: 500 13px var(--font); outline: none; transition: .2s;
}
.nav-search input:focus { border-color: var(--go); box-shadow: 0 0 0 3px color-mix(in srgb, var(--go) 14%, transparent); }
#nav-list { flex: 1; overflow-y: auto; padding: 6px 10px 18px; }
.nav-empty {
  display: grid; gap: 10px; justify-items: start;
  margin: 18px 6px; padding: 16px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--surface);
  color: var(--text-2);
}
.nav-empty b { color: var(--text); font-size: 13.5px; }
.nav-home {
  display: flex; align-items: center; gap: 9px; padding: 10px 12px; margin: 4px 4px 8px;
  border-radius: 8px; font-weight: 600; font-size: 13.5px; color: var(--text-2);
  transition: .18s;
}
.nav-home-ic { display: grid; place-items: center; color: var(--text-3); }
.nav-home:hover { background: var(--surface); color: var(--text); }
.nav-home.active { background: color-mix(in srgb, var(--go) 10%, transparent);
  color: var(--text); }
.nav-home.active .nav-home-ic { color: var(--go); }

.nav-part { margin: 10px 4px 2px; }
.nav-part-head {
  display: flex; justify-content: space-between; align-items: center;
  padding: 6px 10px; font-size: 10.5px; font-weight: 700; letter-spacing: .4px;
  text-transform: uppercase; color: var(--text-3);
}
.nav-part-count { font: 600 10px var(--mono); color: var(--text-3);
  background: var(--surface-2); padding: 2px 7px; border-radius: 20px; }
.nav-item {
  display: flex; align-items: center; gap: 11px; padding: 8px 10px; border-radius: 8px;
  color: var(--text-2); transition: background .16s, color .16s, transform .16s var(--ease-pop); position: relative;
}
.nav-item:hover { background: var(--surface); color: var(--text); transform: translateX(2px); }
.nav-item.active { background: var(--surface-2); color: var(--text); }
.nav-item.active::before { content: ""; position: absolute; left: -10px; top: 8px; bottom: 8px;
  width: 3px; border-radius: 3px; background: var(--go); animation: bar-grow .3s var(--ease-pop) both; }
@keyframes bar-grow { from { transform: scaleY(0); } }
.nav-num {
  flex: none; width: 24px; height: 24px; border-radius: 6px; display: grid; place-items: center;
  font: 700 11px var(--mono); background: var(--surface-3); color: var(--text-2);
}
.nav-item.done .nav-num { background: color-mix(in srgb, var(--good) 16%, transparent); color: var(--good); }
.nav-item.active .nav-num { background: var(--go); color: #04121c; }
.nav-text { flex: 1; min-width: 0; }
.nav-title { display: block; font-size: 12.8px; font-weight: 500; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.nav-bar { display: block; height: 3px; border-radius: 3px; background: var(--surface-3); margin-top: 5px; overflow: hidden; }
.nav-bar > span { display: block; height: 100%; background: var(--go); border-radius: 3px; transition: width .4s var(--ease); }

.sidebar-foot {
  border-top: 1px solid var(--border-soft); padding: 14px 18px;
  display: flex; align-items: center; gap: 12px;
}
.sf-ring { width: 54px; height: 54px; }
.sidebar-foot b { font: 700 16px var(--mono); display: block; }
.sidebar-foot span { font-size: 11px; color: var(--text-3); }

/* ----------------------------------------------------------- main */
#main { padding: 34px clamp(20px, 4vw, 56px) 80px; max-width: calc(var(--maxw) + 120px); margin: 0 auto; width: 100%; min-width: 0; }
section, .module > * { animation: rise .55s var(--ease-pop) both; }
@keyframes rise { from { opacity: 0; transform: translateY(10px); } }

/* ----------------------------------------------------------- hero */
.hero {
  display: grid; grid-template-columns: 1.3fr .8fr .9fr; gap: 30px; align-items: center;
  padding: 22px 0 34px; margin-bottom: 8px;
}
.hero-gopher { display: flex; justify-content: center; align-items: center; min-width: 0; }
.hero-gopher canvas { width: 100%; max-width: 280px; height: 300px; display: block; }
.hero-badges { display: flex; gap: 8px; margin-bottom: 16px; }
.chip {
  font: 600 11px var(--font); padding: 4px 11px; border-radius: 20px;
  background: var(--surface-2); color: var(--text-2); border: 1px solid var(--border);
}
.chip.glow { color: var(--go); border-color: color-mix(in srgb, var(--go) 35%, transparent);
  background: color-mix(in srgb, var(--go) 8%, transparent); }
.chip.ghost { background: transparent; }
.chip.done-chip { color: var(--good); border-color: color-mix(in srgb, var(--good) 35%, transparent); background: color-mix(in srgb, var(--good) 8%, transparent); }
.hero h1 { font: 700 clamp(28px, 4vw, 44px)/1.12 var(--font-serif); letter-spacing: 0; margin: 0 0 10px;
  color: var(--text); }
.hero-sub { color: var(--go-deep); font: italic 600 15px var(--font-serif); margin: 0 0 14px; }
:root[data-theme="dark"] .hero-sub { color: var(--go-soft); }
.hero-tag { color: var(--text-2); font-size: 15px; max-width: 46ch; margin: 0 0 22px; }
.hero-cta { display: flex; gap: 12px; flex-wrap: wrap; }

.btn {
  display: inline-flex; align-items: center; gap: 8px; padding: 11px 18px; border-radius: 8px;
  font: 600 13.5px var(--font); cursor: pointer; border: 1px solid transparent;
  transition: transform .18s var(--ease-pop), box-shadow .2s var(--ease), background .2s var(--ease);
}
.btn.primary { background: var(--go); color: #04121c; }
.btn.primary:hover { background: var(--go-deep); transform: translateY(-2px); box-shadow: 0 10px 22px -10px color-mix(in srgb, var(--go) 55%, transparent); }
.btn.primary:active { transform: translateY(0) scale(.96); }
.hero-cta .btn.primary { animation: cta-pulse 2s ease-out 2, rise .55s var(--ease-pop) both; }
@keyframes cta-pulse {
  0% { box-shadow: 0 0 0 0 color-mix(in srgb, var(--go) 45%, transparent); }
  70% { box-shadow: 0 0 0 12px color-mix(in srgb, var(--go) 0%, transparent); }
  100% { box-shadow: 0 0 0 0 color-mix(in srgb, var(--go) 0%, transparent); }
}
.btn.ghost { background: var(--surface-2); border-color: var(--border); color: var(--text); }
.btn.ghost:hover { border-color: var(--go); color: var(--go); transform: translateY(-2px); }
.btn.ghost:active { transform: translateY(0) scale(.96); }
.btn.small { padding: 8px 14px; font-size: 12.5px; }

.hero-ring { display: flex; flex-direction: column; align-items: center; gap: 20px; }
.ring-wrap { position: relative; width: 132px; height: 132px; }
.ring circle { transition: stroke-dashoffset .8s var(--ease); }
.ring-center { position: absolute; inset: 0; display: grid; place-content: center; text-align: center; }
.ring-pct { font: 700 28px var(--mono); }
.ring-lbl { font-size: 10.5px; color: var(--text-3); }
.hero-stats { display: flex; gap: 26px; }
.hero-stats div { text-align: center; }
.hero-stats b { font: 700 22px var(--mono); display: block; color: var(--go); }
.hero-stats span { font-size: 11px; color: var(--text-3); }

.capstone-banner {
  display: flex; align-items: center; gap: 14px; padding: 16px 20px; margin: 6px 0 30px;
  border-radius: var(--radius); border: 1px solid var(--border); border-left: 3px solid var(--purple);
  background: var(--surface);
}
.capstone-banner .cap-ico { color: var(--warn); display: inline-grid; place-items: center; flex: none; }
.capstone-banner div { font-size: 14px; color: var(--text-2); }
.capstone-banner b { color: var(--text); }

.capstone-map {
  margin: 0 0 34px;
  padding: 20px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
}
.capstone-map-head {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  margin-bottom: 18px;
}
.capstone-map-head .cap-ico {
  width: 40px;
  height: 40px;
  border-radius: 8px;
  display: grid;
  place-items: center;
  flex: none;
  color: var(--go);
  background: color-mix(in srgb, var(--go) 12%, transparent);
  border: 1px solid color-mix(in srgb, var(--go) 26%, transparent);
}
.capstone-map-head h2 {
  margin: 0 0 5px;
  font: 700 22px/1.2 var(--font-serif);
  letter-spacing: 0;
}
.capstone-map-head p {
  margin: 0;
  max-width: 760px;
  color: var(--text-2);
  font-size: 14px;
  line-height: 1.55;
}
.capstone-map-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
}
.capstone-part {
  min-width: 0;
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-sm);
  background: var(--surface-2);
  overflow: hidden;
}
.capstone-part-head {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 11px 13px;
  border-bottom: 1px solid var(--border-soft);
}
.capstone-part-head span {
  font: 700 10.5px var(--mono);
  color: var(--go);
  white-space: nowrap;
}
.capstone-part-head b {
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  font-size: 13px;
}
.capstone-steps {
  display: flex;
  flex-direction: column;
}
.capstone-step {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  gap: 11px;
  min-height: 58px;
  padding: 10px 13px;
  border-bottom: 1px solid var(--border-soft);
  color: var(--text);
  text-decoration: none;
  transition: background .18s var(--ease), color .18s var(--ease);
}
.capstone-step:last-child { border-bottom: 0; }
.capstone-step:hover {
  background: color-mix(in srgb, var(--go) 8%, transparent);
  color: var(--text);
}
.capstone-step-code {
  min-width: 40px;
  padding: 4px 7px;
  border-radius: 7px;
  text-align: center;
  color: var(--go);
  background: color-mix(in srgb, var(--go) 10%, transparent);
  border: 1px solid color-mix(in srgb, var(--go) 22%, transparent);
  font: 700 11px var(--mono);
}
.capstone-step-main {
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: 2px;
}
.capstone-step-main b {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  font-size: 13px;
}
.capstone-step-main span {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  color: var(--text-3);
  font-size: 12px;
}
.capstone-step-open {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  color: var(--text-3);
  font: 600 11px var(--mono);
  white-space: nowrap;
}

.final-code {
  margin: 0 0 36px;
  padding: 20px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
}
.final-code-head {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  margin-bottom: 16px;
}
.final-code-head .cap-ico {
  width: 40px;
  height: 40px;
  border-radius: 8px;
  display: grid;
  place-items: center;
  flex: none;
  color: var(--purple);
  background: color-mix(in srgb, var(--purple) 12%, transparent);
  border: 1px solid color-mix(in srgb, var(--purple) 26%, transparent);
}
.final-code h2 {
  margin: 0 0 5px;
  font: 700 22px/1.2 var(--font-serif);
  letter-spacing: 0;
}
.final-code p {
  margin: 0 0 8px;
  max-width: 900px;
  color: var(--text-2);
  font-size: 14px;
  line-height: 1.55;
}
.final-code-meta {
  display: inline-flex;
  align-items: center;
  padding: 4px 9px;
  border-radius: 7px;
  color: var(--purple);
  background: color-mix(in srgb, var(--purple) 10%, transparent);
  border: 1px solid color-mix(in srgb, var(--purple) 24%, transparent);
  font: 700 11px var(--mono);
}
.project-files {
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.project-file {
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-sm);
  background: var(--surface-2);
  overflow: hidden;
}
.project-file summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  min-height: 48px;
  padding: 11px 13px;
  cursor: pointer;
  color: var(--text);
  font: 700 13px var(--mono);
  list-style: none;
}
.project-file summary::-webkit-details-marker { display: none; }
.project-file summary::before {
  content: "›";
  color: var(--go);
  font-size: 18px;
  line-height: 1;
  transition: transform .2s var(--ease);
}
.project-file[open] summary::before { transform: rotate(90deg); }
.project-file summary span {
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  flex: 1;
}
.project-file summary b {
  color: var(--text-3);
  font: 700 10.5px var(--mono);
  text-transform: uppercase;
}
.project-file .code {
  border-width: 1px 0 0;
  border-radius: 0;
}

/* ----------------------------------------------------- module cards */
.part-block { margin-bottom: 38px; }
.part-head { display: flex; justify-content: space-between; align-items: flex-end; margin: 0 0 16px; gap: 12px; }
.part-label { font: 700 11px var(--mono); color: var(--go); letter-spacing: 1px; }
.part-head h3 { margin: 3px 0 0; font: 700 19px var(--font-serif); letter-spacing: 0; }
.part-level { font-size: 12px; color: var(--text-3); white-space: nowrap; }
.card-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(290px, 1fr)); gap: 16px; }

.mod-card {
  position: relative; padding: 18px; border-radius: var(--radius);
  background: var(--surface); border: 1px solid var(--border); overflow: hidden;
  transition: border-color .25s var(--ease), transform .25s var(--ease-pop), box-shadow .25s var(--ease);
  display: flex; flex-direction: column; min-height: 200px;
  animation: card-in .5s var(--ease-pop) both;
}
@keyframes card-in { from { opacity: 0; transform: translateY(14px) scale(.97); } }
.card-grid .mod-card:nth-child(1) { animation-delay: .02s; }
.card-grid .mod-card:nth-child(2) { animation-delay: .06s; }
.card-grid .mod-card:nth-child(3) { animation-delay: .10s; }
.card-grid .mod-card:nth-child(4) { animation-delay: .14s; }
.card-grid .mod-card:nth-child(5) { animation-delay: .18s; }
.card-grid .mod-card:nth-child(6) { animation-delay: .22s; }
.card-grid .mod-card:nth-child(n+7) { animation-delay: .26s; }
.mod-card:hover {
  border-color: color-mix(in srgb, var(--go) 45%, var(--border));
  transform: translateY(-5px);
  box-shadow: 0 16px 32px -18px color-mix(in srgb, var(--go) 45%, transparent), var(--shadow);
}
.mod-card:hover .mod-ic { transform: scale(1.1) rotate(-4deg); }
.mod-card-top { display: flex; align-items: center; gap: 10px; margin-bottom: 12px; }
.mod-ic { width: 38px; height: 38px; border-radius: 8px; display: grid; place-items: center;
  background: color-mix(in srgb, var(--go) 12%, transparent); color: var(--go); border: 1px solid color-mix(in srgb, var(--go) 22%, transparent);
  transition: transform .3s var(--ease-pop); }
.mod-card-num { font: 700 11px var(--mono); color: var(--text-3); margin-left: 2px; }
.mod-check { margin-left: auto; width: 22px; height: 22px; border-radius: 50%; background: color-mix(in srgb, var(--good) 16%, transparent); color: var(--good); display: grid; place-items: center; font-size: 13px; font-weight: 700; animation: check-pop .35s var(--ease-pop); }
.mod-card.done { border-color: color-mix(in srgb, var(--good) 30%, var(--border)); }
.mod-card h4 { margin: 0 0 7px; font-size: 15.5px; letter-spacing: 0; line-height: 1.3; font-weight: 700; }
.mod-card p { margin: 0 0 14px; font-size: 12.8px; color: var(--text-2); flex: 1; }
.mod-card-foot { display: flex; align-items: center; gap: 7px; flex-wrap: wrap; }
.mod-anim-tag { margin-left: auto; font-size: 11px; color: var(--purple); font-weight: 600; display: inline-flex; align-items: center; gap: 5px; }
.mod-card-bar { position: absolute; left: 0; right: 0; bottom: 0; height: 3px; background: var(--surface-3); }
.mod-card-bar > span { display: block; height: 100%; background: var(--go); transition: width .5s var(--ease); }

/* verification table */
.verify { margin-top: 18px; }
.verify h3 { font: 700 18px var(--font-serif); margin: 0 0 14px; letter-spacing: 0; }
.verify-table { width: 100%; border-collapse: collapse; border-radius: var(--radius); overflow: hidden; border: 1px solid var(--border); }
.verify-table td { padding: 13px 16px; border-bottom: 1px solid var(--border-soft); font-size: 13.5px; vertical-align: top; }
.verify-table tr:last-child td { border-bottom: none; }
.verify-table td:first-child { width: 230px; font-weight: 600; color: var(--text); background: var(--surface-2); }
.verify-table td:last-child { color: var(--text-2); }
.inl { font: 500 12px var(--mono); background: var(--surface-3); padding: 1px 6px; border-radius: 5px; color: var(--go-deep); }
:root[data-theme="dark"] .inl { color: var(--go-soft); }

.foot {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 14px;
  flex-wrap: wrap;
  margin-top: 40px;
  padding-top: 20px;
  border-top: 1px solid var(--border-soft);
  font-size: 12px;
  color: var(--text-3);
  text-align: center;
}
.foot-links { display: inline-flex; align-items: center; gap: 8px; }
.foot-links a {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  min-height: 32px;
  padding: 6px 10px;
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text-2);
  text-decoration: none;
  transition: color .18s var(--ease), border-color .18s var(--ease), background .18s var(--ease);
}
.foot-links a:hover {
  color: var(--go);
  border-color: color-mix(in srgb, var(--go) 45%, var(--border));
  background: color-mix(in srgb, var(--go) 8%, transparent);
}

/* ----------------------------------------------------------- module */
.module { max-width: var(--maxw); margin: 0 auto; min-width: 0; }
.mod-breadcrumb { display: flex; align-items: center; gap: 8px; font-size: 12px; color: var(--text-3); margin-bottom: 18px; flex-wrap: wrap; }
.mod-breadcrumb a:hover { color: var(--go); }
.bc-cur { color: var(--text-2); }
.mod-header { display: flex; gap: 18px; margin-bottom: 30px; }
.mod-h-ic { flex: none; width: 56px; height: 56px; border-radius: 12px; display: grid; place-items: center;
  background: color-mix(in srgb, var(--go) 14%, transparent);
  color: var(--go); border: 1px solid color-mix(in srgb, var(--go) 26%, transparent); }
.mod-header > div:last-child { min-width: 0; }
.mod-h-meta { display: flex; gap: 7px; margin-bottom: 9px; }
.mod-header h1 { font: 700 clamp(22px, 3vw, 30px)/1.2 var(--font-serif); margin: 0 0 8px; letter-spacing: 0; }
.mod-header p { margin: 0; color: var(--text-2); font-size: 14.5px; max-width: 70ch; }

.card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 20px; }
.block { margin: 34px 0; }
.block-h { font: 700 18px var(--font-serif); letter-spacing: 0; margin: 0 0 16px; display: flex; align-items: center; gap: 10px; }
.block-h::before { content: ""; width: 4px; height: 18px; border-radius: 3px; background: var(--go); }

/* ------------------------------------------------- visualization */
.viz { margin: 26px 0; padding: 0; overflow: hidden; border: 1px solid var(--border); border-radius: var(--radius); overflow-anchor: none; }
.viz-head { display: flex; justify-content: space-between; align-items: center; padding: 18px 20px 4px; }
.viz-head > div { min-width: 0; }
.viz-tag { font: 700 11px var(--font); letter-spacing: .5px; color: var(--purple); text-transform: uppercase; display: inline-flex; align-items: center; gap: 6px; }
.viz-head h2 { margin: 6px 0 0; font: 700 19px var(--font-serif); letter-spacing: 0; }
.viz-count { font: 700 11px var(--mono); color: var(--text-3); background: var(--surface-2);
  border: 1px solid var(--border); padding: 3px 9px; border-radius: 20px; align-self: flex-start; }
.viz-blurb { padding: 0 20px; margin: 6px 0 14px; color: var(--text-2); font-size: 13.5px; max-width: 75ch; }
.viz-stage { position: relative; margin: 0 16px; border-radius: 8px; overflow: hidden; border: 1px solid var(--border);
  background: var(--anim-bg); }
.viz-stage canvas { display: block; width: 100%; height: 380px; }
.viz-caption {
  margin: 12px 18px 0; padding: 10px 14px; border-radius: 8px; min-height: 40px;
  background: var(--surface-2); border: 1px solid var(--border-soft);
  font-size: 13.5px; color: var(--text); display: flex; flex-direction: column; gap: 6px; justify-content: center;
  border-left: 3px solid var(--go);
}
.viz-why { display: block; font-size: 12.5px; color: var(--warn); }
.viz-why b { color: var(--warn); }
.viz-controls { display: flex; align-items: center; gap: 9px; padding: 14px 18px 18px; }
.vc-btn { width: 38px; height: 38px; border-radius: 8px; background: var(--surface-2); border: 1px solid var(--border);
  color: var(--text); cursor: pointer; font-size: 14px; display: grid; place-items: center;
  transition: transform .18s var(--ease-pop), border-color .18s, color .18s, background .18s; }
.vc-btn:hover { border-color: var(--go); color: var(--go); transform: scale(1.08); }
.vc-btn:active { transform: scale(.92); }
.vc-btn.play { background: var(--go); color: #04121c; border: none; width: 44px; height: 44px; font-size: 15px; }
.vc-btn.play.playing { background: var(--surface-3); color: var(--text); animation: breathe 1.6s ease-in-out infinite; }
@keyframes breathe {
  0%, 100% { box-shadow: 0 0 0 0 color-mix(in srgb, var(--go) 35%, transparent); }
  50% { box-shadow: 0 0 0 7px color-mix(in srgb, var(--go) 0%, transparent); }
}
.viz-controls input[type="range"] { flex: 1; appearance: none; height: 6px; border-radius: 6px; background: var(--surface-3); outline: none; cursor: pointer; }
.viz-controls input[type="range"]::-webkit-slider-thumb { appearance: none; width: 16px; height: 16px; border-radius: 50%;
  background: var(--go); cursor: pointer; box-shadow: 0 0 0 4px color-mix(in srgb, var(--go) 18%, transparent); }
.viz-controls input[type="range"]::-moz-range-thumb { width: 16px; height: 16px; border: none; border-radius: 50%; background: var(--go); }
.vc-speed { font: 500 11px var(--mono); color: var(--text-3); white-space: nowrap; }

/* ---------------------------------------------------- concepts */
.concepts { display: flex; flex-direction: column; gap: 10px; }
.concept { border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface); overflow: hidden; transition: border-color .2s; }
.concept.open { border-color: color-mix(in srgb, var(--go) 35%, var(--border)); }
.concept-head { width: 100%; display: flex; align-items: center; gap: 14px; padding: 15px 18px; background: none; border: none;
  color: var(--text); cursor: pointer; text-align: left; font: 600 14.5px var(--font); }
.concept-n { font: 700 12px var(--mono); color: var(--go); flex: none; }
.concept-t { flex: 1; letter-spacing: 0; }
.concept-chev { color: var(--text-3); transition: transform .3s var(--ease-pop); font-size: 12px; }
.concept.open .concept-chev { transform: rotate(180deg); }
.concept-body { display: grid; grid-template-rows: 0fr; transition: grid-template-rows .35s var(--ease-pop); }
.concept.open .concept-body { grid-template-rows: 1fr; }
.concept-inner { overflow: hidden; min-height: 0; }
.concept.open .concept-inner { padding-bottom: 4px; }
.concept-body p { margin: 0 18px 14px; color: var(--text-2); font-size: 13.8px; }
.concept-body .code { margin: 0 18px 18px; }

/* code blocks */
.code { border-radius: var(--radius-sm); border: 1px solid var(--border); overflow: hidden; background: var(--anim-bg); }
.code-head { display: flex; justify-content: space-between; align-items: center; padding: 7px 12px; background: var(--surface-2); border-bottom: 1px solid var(--border-soft); }
.code-lang { font: 600 10.5px var(--mono); color: var(--go); text-transform: uppercase; letter-spacing: 1px; }
.copy-btn { font: 600 11px var(--font); background: var(--surface-3); border: 1px solid var(--border); color: var(--text-2);
  padding: 4px 10px; border-radius: 6px; cursor: pointer; transition: transform .2s var(--ease-pop), border-color .18s, color .18s; }
.copy-btn:hover { border-color: var(--go); color: var(--go); transform: translateY(-1px); }
.copy-btn.ok { color: var(--good); border-color: var(--good); animation: check-pop .3s var(--ease-pop); }
.copy-btn.small { padding: 3px 9px; }
.code pre { margin: 0; padding: 14px 16px; overflow-x: auto; }
.code code { font: 500 12.8px/1.65 var(--mono); color: var(--text); white-space: pre; }
.t-com { color: var(--t-com); font-style: italic; }
.t-str { color: var(--t-str); }
.t-num { color: var(--t-num); }
.t-kw { color: var(--t-kw); font-weight: 600; }
.t-bi { color: var(--t-bi); }
.t-fn { color: var(--t-fn); }

/* two column */
.two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin: 16px 0; }
.two-col .card h3 { margin: 0 0 10px; font-size: 15.5px; display: flex; align-items: center; gap: 9px; }
.two-col .card p { margin: 0 0 12px; color: var(--text-2); font-size: 13.5px; }
.dot-ai, .dot-cap { width: 9px; height: 9px; border-radius: 50%; flex: none; }
.dot-ai { background: var(--purple); }
.dot-cap { background: var(--warn); }
.ai-card { border-left: 3px solid var(--purple); }
.prompt { border: 1px solid var(--border); border-radius: var(--radius-sm); overflow: hidden; }
.prompt-head { display: flex; justify-content: space-between; align-items: center; padding: 7px 12px; background: var(--surface-2); border-bottom: 1px solid var(--border-soft); font: 600 11px var(--mono); color: var(--purple); }
.prompt-body { margin: 0; padding: 12px 14px; font: 500 12.5px/1.55 var(--mono); color: var(--text-2); background: var(--anim-bg); white-space: pre-wrap; }
.cap-card { border-left: 3px solid var(--warn); }
.cap-tag { display: inline-block; font: 600 11px var(--mono); color: var(--warn); background: color-mix(in srgb, var(--warn) 10%, transparent); border: 1px solid color-mix(in srgb, var(--warn) 30%, transparent); padding: 4px 10px; border-radius: 8px; }

/* checklist + notes */
.checklist { list-style: none; margin: 0 0 14px; padding: 0; display: flex; flex-direction: column; gap: 8px; }
.check { display: flex; align-items: flex-start; gap: 11px; padding: 9px 11px; border-radius: 8px; cursor: pointer;
  background: var(--surface-2); border: 1px solid var(--border-soft); font-size: 13px; color: var(--text-2); transition: .16s; }
.check:hover { border-color: var(--border); }
.check-box { flex: none; width: 20px; height: 20px; border-radius: 5px; border: 1.5px solid var(--border); display: grid; place-items: center;
  font-size: 12px; font-weight: 700; color: transparent; transition: transform .3s var(--ease-pop), background .18s, border-color .18s, color .18s; }
.check.on { color: var(--text); }
.check.on .check-box { background: var(--good); border-color: var(--good); color: #04121c; animation: check-pop .3s var(--ease-pop); }
@keyframes check-pop { from { transform: scale(.5); } 60% { transform: scale(1.15); } }
.notes { width: 100%; min-height: 130px; resize: vertical; padding: 12px 14px; border-radius: var(--radius-sm);
  background: var(--anim-bg); border: 1px solid var(--border); color: var(--text); font: 500 13px/1.6 var(--font); outline: none; transition: .2s; }
.notes:focus { border-color: var(--go); box-shadow: 0 0 0 3px color-mix(in srgb, var(--go) 10%, transparent); }
.notes-status { font: 600 11px var(--mono); color: var(--good); display: inline-block; margin-top: 6px; height: 14px; }

.mod-nav { display: flex; justify-content: space-between; align-items: center; gap: 12px; margin-top: 30px; padding-top: 22px; border-top: 1px solid var(--border-soft); }

/* nav scrim (mobile) */
.nav-scrim { display: none; position: fixed; inset: 0; background: rgba(0,0,0,.5); z-index: 30; }

/* -------------------------------------------- in plain terms callout */
.plain { display: flex; gap: 14px; align-items: flex-start; padding: 15px 18px; margin: 0 0 4px;
  border-radius: var(--radius); border: 1px solid var(--border); border-left: 3px solid var(--warn);
  background: var(--surface); }
.plain-ic { color: var(--warn); line-height: 1.3; display: inline-grid; place-items: center; flex: none; }
.plain > div { min-width: 0; }
.plain-k { display: block; font: 700 10.5px var(--font); letter-spacing: .6px; text-transform: uppercase; color: var(--warn); margin-bottom: 3px; }
.plain p { margin: 0; color: var(--text); font-size: 14px; line-height: 1.6; }

.module-build {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  margin: 14px 0 18px;
  padding: 16px 18px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
}
.module-build.cap-build { border-left: 3px solid var(--warn); }
.module-build.practice-build { border-left: 3px solid var(--go); }
.build-ic {
  width: 36px;
  height: 36px;
  border-radius: 8px;
  display: grid;
  place-items: center;
  flex: none;
  color: var(--warn);
  background: color-mix(in srgb, var(--warn) 12%, transparent);
  border: 1px solid color-mix(in srgb, var(--warn) 26%, transparent);
}
.practice-build .build-ic {
  color: var(--go);
  background: color-mix(in srgb, var(--go) 12%, transparent);
  border-color: color-mix(in srgb, var(--go) 26%, transparent);
}
.module-build > div { min-width: 0; }
.build-k {
  display: block;
  margin-bottom: 4px;
  color: var(--text-3);
  font: 700 10.5px var(--font);
  letter-spacing: .6px;
  text-transform: uppercase;
}
.module-build h2 {
  margin: 0 0 6px;
  font: 700 18px/1.25 var(--font-serif);
  letter-spacing: 0;
}
.module-build p {
  margin: 0 0 10px;
  color: var(--text-2);
  font-size: 13.8px;
  line-height: 1.6;
}
.module-build .practice-steps { margin-top: 8px; }
.module-build .practice-steps li { font-size: 13px; }

/* -------------------------------------------------- step indicator */
.viz-steps { padding: 14px 18px 0; }
.steps-dots { display: flex; gap: 8px; flex-wrap: wrap; }
.step-dot { position: relative; width: 30px; height: 30px; border-radius: 50%; padding: 0;
  display: grid; place-items: center; background: var(--surface-2); border: 1px solid var(--border);
  color: var(--text-3); cursor: pointer; transition: transform .2s var(--ease-pop), background .18s, border-color .18s, color .18s; }
.step-dot b { font: 700 12px var(--mono); }
.step-dot span { display: none; }
.step-dot:hover { border-color: var(--go); color: var(--text); transform: scale(1.12); }
.step-dot.done { background: color-mix(in srgb, var(--good) 14%, transparent); border-color: color-mix(in srgb, var(--good) 35%, transparent); color: var(--good); }
.step-dot.active { background: var(--go); border-color: var(--go); color: #04121c; transform: scale(1.15);
  animation: dot-pulse 1.8s ease-in-out infinite; }
@keyframes dot-pulse {
  0%, 100% { box-shadow: 0 0 0 0 color-mix(in srgb, var(--go) 40%, transparent); }
  50% { box-shadow: 0 0 0 6px color-mix(in srgb, var(--go) 0%, transparent); }
}
.steps-now { display: flex; align-items: center; gap: 10px; margin-top: 11px; }
.steps-badge { font: 700 11px var(--mono); color: var(--go); background: color-mix(in srgb, var(--go) 10%, transparent);
  border: 1px solid color-mix(in srgb, var(--go) 30%, transparent); padding: 3px 9px; border-radius: 6px; white-space: nowrap; flex: none; }
.steps-title { font-size: 13.5px; font-weight: 600; color: var(--text); }
.vc-btn.speed { width: auto; padding: 0 12px; font: 600 12px var(--mono); }

/* ----------------------------------------------------- practice card */
.practice-card { border-left: 3px solid var(--go); }
.dot-practice { width: 9px; height: 9px; border-radius: 50%; background: var(--go); flex: none; }
.practice-steps { margin: 6px 0 0; padding: 0; list-style: none; counter-reset: step; display: flex; flex-direction: column; gap: 10px; }
.practice-steps li { position: relative; padding-left: 34px; font-size: 13px; color: var(--text-2); counter-increment: step; line-height: 1.5; }
.practice-steps li::before { content: counter(step); position: absolute; left: 0; top: -1px; width: 23px; height: 23px;
  border-radius: 6px; background: var(--surface-3); color: var(--go); font: 700 11px var(--mono); display: grid; place-items: center; }

/* --------------------------------------------- pitfalls / takeaways */
.pitfalls-card h3, .takeaways-card h3 { display: flex; align-items: center; gap: 9px; }
.ic-pill { width: 24px; height: 24px; border-radius: 6px; display: grid; place-items: center; flex: none; }
.ic-pill.warn { color: var(--warn); background: color-mix(in srgb, var(--warn) 14%, transparent); }
.ic-pill.key { color: var(--go); background: color-mix(in srgb, var(--go) 14%, transparent); }
.pitfalls, .takeaways { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 11px; }
.pitfalls li, .takeaways li { position: relative; padding-left: 24px; font-size: 13px; color: var(--text-2); line-height: 1.5; }
.pitfalls li::before { content: "✕"; position: absolute; left: 2px; top: 0; color: var(--bad); font-weight: 700; font-size: 12px; }
.takeaways li::before { content: "✓"; position: absolute; left: 2px; top: 0; color: var(--good); font-weight: 700; }
.pitfalls-card { border-left: 3px solid var(--bad); }
.takeaways-card { border-left: 3px solid var(--good); }

/* --------------------------------------------- AI prompt clarity */
.prompt-k { font: 600 11px var(--font); color: var(--purple); display: inline-flex; align-items: center; gap: 6px; }
.prompt-note { margin: 10px 0 0; font-size: 12px; color: var(--text-3); line-height: 1.5; }
.prompt-note em { color: var(--text-2); font-style: italic; }

/* ----------------------------------------------------- assignments */
.assign-score { margin-left: auto; font: 600 11px var(--mono); color: var(--go);
  background: color-mix(in srgb, var(--go) 10%, transparent); border: 1px solid color-mix(in srgb, var(--go) 30%, transparent);
  padding: 3px 10px; border-radius: 20px; }
.assign-intro { margin: -6px 0 14px; font-size: 13px; color: var(--text-3); max-width: 80ch; }
.assigns { display: flex; flex-direction: column; gap: 14px; }
.assign { border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface); padding: 18px; transition: border-color .2s; }
.assign.is-solved { border-color: color-mix(in srgb, var(--good) 35%, var(--border)); }
.assign-head { display: flex; align-items: center; gap: 11px; margin-bottom: 10px; }
.assign-n { width: 26px; height: 26px; border-radius: 7px; display: grid; place-items: center;
  background: var(--surface-3); color: var(--go); font: 700 12px var(--mono); flex: none; }
.assign.is-solved .assign-n { background: var(--good); color: #04121c; }
.assign-kind { font: 600 10.5px var(--font); letter-spacing: .4px; text-transform: uppercase; color: var(--text-3);
  border: 1px solid var(--border); padding: 2px 9px; border-radius: 20px; }
.assign-state { margin-left: auto; font: 700 11.5px var(--font); color: var(--good); }
.assign-q { margin: 0 0 12px; font-size: 14px; color: var(--text); font-weight: 500; }
.assign .code { margin-bottom: 12px; }

.opts { display: flex; flex-direction: column; gap: 8px; }
.opt { display: flex; align-items: flex-start; gap: 11px; padding: 10px 12px; border-radius: 8px;
  background: var(--surface-2); border: 1px solid var(--border-soft); cursor: pointer; font-size: 13.5px; color: var(--text-2);
  transition: border-color .15s, background .15s, color .15s, transform .2s var(--ease-pop); }
.opt:hover { border-color: var(--border); color: var(--text); transform: translateX(2px); }
.opt input { accent-color: var(--go); margin-top: 2px; flex: none; width: 15px; height: 15px; }
.opt:has(input:checked) { border-color: var(--go); background: color-mix(in srgb, var(--go) 8%, var(--surface)); color: var(--text); transform: translateX(2px); }

.assign-input { width: 100%; padding: 11px 13px; border-radius: var(--radius-sm); background: var(--anim-bg);
  border: 1px solid var(--border); color: var(--text); font: 600 13.5px var(--mono); outline: none; transition: .2s; }
.assign-input:focus { border-color: var(--go); box-shadow: 0 0 0 3px color-mix(in srgb, var(--go) 10%, transparent); }
.assign-code { width: 100%; min-height: 110px; resize: vertical; padding: 12px 14px; border-radius: var(--radius-sm);
  background: var(--anim-bg); border: 1px solid var(--border); color: var(--text); font: 500 12.8px/1.6 var(--mono); outline: none; white-space: pre; transition: .2s; }
.assign-code:focus { border-color: var(--go); box-shadow: 0 0 0 3px color-mix(in srgb, var(--go) 10%, transparent); }

.assign-foot { display: flex; gap: 9px; margin-top: 12px; }
.assign-out { margin-top: 12px; display: flex; flex-direction: column; gap: 6px; }
.assign-out:empty { margin-top: 0; }
.chk { font: 500 12.5px var(--mono); padding: 6px 11px; border-radius: 6px; display: flex; align-items: center; gap: 8px; }
.chk.ok { color: var(--good); background: color-mix(in srgb, var(--good) 8%, transparent); }
.chk.no { color: var(--bad); background: color-mix(in srgb, var(--bad) 8%, transparent); }
.assign-verdict { font: 700 13px var(--font); padding: 9px 13px; border-radius: 8px; margin-top: 2px; animation: verdict-in .35s var(--ease-pop) both; }
.assign-verdict.ok { color: var(--good); background: color-mix(in srgb, var(--good) 10%, transparent); border: 1px solid color-mix(in srgb, var(--good) 30%, transparent); }
.assign-verdict.no { color: var(--bad); background: color-mix(in srgb, var(--bad) 8%, transparent); border: 1px solid color-mix(in srgb, var(--bad) 28%, transparent); }
@keyframes verdict-in { from { opacity: 0; transform: translateY(-6px) scale(.96); } }
.assign-exp { margin-top: 12px; padding: 12px 14px; border-radius: var(--radius-sm); background: var(--surface-2);
  border-left: 3px solid var(--purple); font-size: 13px; color: var(--text-2); line-height: 1.6; }

/* ----------------------------------------------------- deep-dive lesson */
.lesson .block-h { justify-content: flex-start; }
.lesson-meta { margin-left: auto; font: 600 11px var(--mono); color: var(--text-3);
  background: var(--surface-2); border: 1px solid var(--border); padding: 3px 10px; border-radius: 20px; }
.lesson-body { display: flex; flex-direction: column; gap: 6px; border: 1px solid var(--border);
  border-radius: var(--radius); background: var(--surface); padding: 6px 26px 10px; }
.lesson-sec { padding: 18px 0; border-bottom: 1px solid var(--border-soft); }
.lesson-sec:last-child { border-bottom: none; }
.lesson-sec h4 { display: flex; align-items: center; gap: 11px; margin: 0 0 8px; font: 700 16px var(--font-serif); letter-spacing: 0; color: var(--text); }
.ls-n { flex: none; width: 26px; height: 26px; border-radius: 7px; display: grid; place-items: center;
  background: color-mix(in srgb, var(--go) 14%, transparent); color: var(--go); font: 700 12px var(--mono); }
.lesson-sec p { margin: 0 0 10px; color: var(--text-2); font-size: 14.5px; line-height: 1.7; max-width: none; }
.lesson-sec p:last-of-type { margin-bottom: 0; }
.lesson-sec .code { margin-top: 12px; max-width: 78ch; }
.lesson-sec p .inl { font-size: 12.5px; }

/* ------------------------------------------------------ worked example */
.worked-example .block-h { justify-content: flex-start; }
.we-intro { margin: -6px 0 16px; color: var(--text-2); font-size: 14px; max-width: 80ch; }
.we-steps { display: flex; flex-direction: column; gap: 14px; }
.we-step { border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface); padding: 18px 22px; }
.we-step-head { display: flex; align-items: center; gap: 11px; margin-bottom: 8px; }
.we-step-head h4 { margin: 0; font: 700 15.5px var(--font-serif); letter-spacing: 0; color: var(--text); }
.we-n { flex: none; width: 26px; height: 26px; border-radius: 7px; display: grid; place-items: center;
  background: color-mix(in srgb, var(--purple) 16%, transparent); color: var(--purple); font: 700 12px var(--mono); }
.we-concept { margin: 0 0 4px; color: var(--text-2); font-size: 14px; line-height: 1.65; max-width: 72ch; }
.we-step .code { margin: 12px 0; max-width: 78ch; }
.we-why { margin: 10px 0 0; padding: 9px 13px; border-radius: var(--radius-sm); background: color-mix(in srgb, var(--warn) 6%, transparent);
  border-left: 3px solid var(--warn); font-size: 13px; color: var(--warn); line-height: 1.6; max-width: 78ch; }
.we-why b { color: var(--warn); }

/* --------------------------------------------------------- glossary */
.glossary { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.gterm { display: flex; flex-direction: column; gap: 3px; padding: 12px 14px; border-radius: var(--radius-sm);
  background: var(--surface); border: 1px solid var(--border); border-left: 3px solid var(--go); }
.gt { font: 700 13px var(--mono); color: var(--go-deep); }
:root[data-theme="dark"] .gt { color: var(--go-soft); }
.gd { font-size: 12.8px; color: var(--text-2); line-height: 1.5; }

/* ----------------------------------------------------- video lessons */
.videos { display: flex; flex-direction: column; gap: 10px; }
.video-card {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  overflow: hidden;
}
.video-card-head {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  gap: 14px;
  width: 100%;
  padding: 14px 16px;
  border: 0;
  background: none;
  color: inherit;
  font: inherit;
  text-align: left;
  cursor: pointer;
  transition: background .18s var(--ease);
}
.video-card-head:hover { background: color-mix(in srgb, var(--go) 8%, transparent); }
.video-card-head[aria-expanded="true"] { background: color-mix(in srgb, var(--go) 10%, transparent); }
.video-ic {
  width: 38px; height: 38px; border-radius: 10px; flex: none;
  display: flex; align-items: center; justify-content: center;
  background: color-mix(in srgb, var(--go) 12%, transparent);
  color: var(--go);
}
.video-card-main { min-width: 0; display: flex; flex-direction: column; gap: 3px; }
.video-card-main h4 { margin: 0; font: 700 14.5px var(--font-serif); color: var(--text); }
.video-card-speaker { font-size: 11.5px; font-weight: 700; color: var(--go-deep); }
:root[data-theme="dark"] .video-card-speaker { color: var(--go-soft); }
.video-card-main p { margin: 3px 0 0; font-size: 12.8px; color: var(--text-2); line-height: 1.5; }
.video-open {
  flex: none; display: inline-flex; align-items: center; gap: 4px;
  color: var(--go); font: 600 11px var(--mono); white-space: nowrap;
}
.video-player { display: none; }
.video-player.on { display: block; }
.video-embed {
  position: relative;
  width: 100%;
  aspect-ratio: 16 / 9;
  background: #000;
  border-top: 1px solid var(--border);
}
.video-embed iframe {
  position: absolute; inset: 0; width: 100%; height: 100%; border: 0;
}
.video-ext-link {
  display: block;
  padding: 8px 16px 12px;
  font-size: 11.5px;
  font-weight: 600;
  color: var(--text-3);
  text-decoration: none;
}
.video-ext-link:hover { color: var(--go); }
@media (max-width: 560px) {
  .video-card-head { grid-template-columns: auto minmax(0, 1fr); }
  .video-open { display: none; }
}

/* ------------------------------------------------------- responsive */
@media (max-width: 1080px) {
  /* minmax(0,1fr): the canvas's intrinsic bitmap size (clientWidth x dpr)
     must not inflate the track's auto minimum and overflow the viewport */
  .hero { grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); }
  .hero-text { grid-column: 1 / -1; }
  .hero-gopher canvas { max-width: 240px; height: 250px; }
  .hero-ring { justify-content: center; min-width: 0; }
}
@media (max-width: 880px) {
  .layout { grid-template-columns: 1fr; }
  .nav-toggle { display: grid; }
  .sidebar { position: fixed; top: 0; left: 0; bottom: 0; width: 300px; height: 100vh; z-index: 50;
    transform: translateX(-100%); transition: transform .28s var(--ease); padding-top: 14px; }
  body.nav-open .sidebar { transform: none; box-shadow: var(--shadow); }
  body.nav-open .nav-scrim { display: block; }
  .two-col { grid-template-columns: 1fr; }
  .capstone-map-grid { grid-template-columns: 1fr; }
  .glossary { grid-template-columns: 1fr; }
  .top-progress { display: none; }
}
@media (max-width: 560px) {
  .topbar { padding: 12px 14px; gap: 10px; }
  .topbar-right { gap: 8px; }
  .brand-text small { display: none; }
  #main { padding: 18px 16px 70px; }
  .hero { gap: 18px; padding: 10px 0 18px; margin-bottom: 0; }
  .hero-badges { margin-bottom: 10px; flex-wrap: wrap; }
  .hero h1 { font-size: 26px; line-height: 1.1; margin-bottom: 8px; }
  .hero-sub { margin-bottom: 8px; }
  .hero-tag {
    font-size: 14px; margin-bottom: 14px;
    display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical; overflow: hidden;
  }
  .hero-cta { gap: 8px; }
  .hero-cta .btn { padding: 9px 12px; font-size: 12.5px; }
  .hero-gopher canvas { max-width: 200px; height: 200px; }
  .hero-ring { flex-direction: column; align-items: center; gap: 14px; }
  .ring-wrap { width: 96px; height: 96px; }
  .ring-wrap .ring { width: 96px; height: 96px; }
  .ring-pct { font-size: 21px; }
  .ring-lbl { font-size: 9.5px; }
  .hero-stats { flex: 1; display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 6px; }
  .hero-stats b { font-size: 17px; }
  .hero-stats span { font-size: 10px; line-height: 1.25; }
  .capstone-banner { align-items: flex-start; margin: 0 0 20px; padding: 13px 14px; }
  .capstone-map { padding: 14px; margin-bottom: 24px; }
  .capstone-map-head { gap: 11px; margin-bottom: 14px; }
  .capstone-map-head .cap-ico { width: 34px; height: 34px; }
  .capstone-map-head h2 { font-size: 18px; }
  .capstone-map-head p { font-size: 12.8px; }
  .capstone-part-head { padding: 10px 11px; align-items: flex-start; flex-direction: column; gap: 3px; }
  .capstone-part-head b { white-space: normal; line-height: 1.35; }
  .capstone-step { grid-template-columns: auto minmax(0, 1fr) auto; gap: 9px; padding: 10px 11px; }
  .capstone-step-code { min-width: 36px; }
  .capstone-step-main b, .capstone-step-main span { white-space: normal; display: -webkit-box; -webkit-box-orient: vertical; overflow: hidden; }
  .capstone-step-main b { -webkit-line-clamp: 1; }
  .capstone-step-main span { -webkit-line-clamp: 2; }
  .capstone-step-open { font-size: 0; gap: 0; }
  .capstone-step-open svg { width: 18px; height: 18px; }
  .final-code { padding: 14px; margin-bottom: 24px; }
  .final-code-head { gap: 11px; margin-bottom: 14px; }
  .final-code-head .cap-ico { width: 34px; height: 34px; }
  .final-code h2 { font-size: 18px; }
  .final-code p { font-size: 12.8px; }
  .project-file summary { align-items: flex-start; min-height: 46px; padding: 10px 11px; }
  .project-file summary span { white-space: normal; overflow-wrap: anywhere; }
  .module-build { padding: 14px; gap: 12px; }
  .build-ic { width: 34px; height: 34px; }
  .module-build h2 { font-size: 16.5px; }
  .part-block { margin-bottom: 28px; }
  .mod-header { flex-direction: column; gap: 12px; }
  .viz-stage canvas { height: 320px; }
  .card-grid { grid-template-columns: 1fr; }
  .verify-table td:first-child { width: 130px; }
  .foot { align-items: stretch; flex-direction: column; gap: 10px; }
  .foot-links { justify-content: center; flex-wrap: wrap; }
}

/* ------------------------------------------------- micro-interactions */
/* route transition: #main content slides up as a page enters */
.page-enter { animation: page-in .4s var(--ease) both; }
@keyframes page-in {
  from { opacity: 0; transform: translateY(12px); }
}

/* scroll reveal: elements fade-rise the first time they enter the viewport.
   .reveal is only ever added when IntersectionObserver exists (see app.js),
   so content can never be stranded invisible. */
.reveal { opacity: 0; transform: translateY(16px);
  transition: opacity .55s var(--ease), transform .55s var(--ease); }
.reveal.revealed { opacity: 1; transform: none; }

/* module-completion celebration */
.celebrate-overlay {
  position: fixed; inset: 0; z-index: 90; pointer-events: none;
  display: grid; place-items: center;
}
.celebrate-overlay canvas { position: absolute; inset: 0; width: 100%; height: 100%; }
.celebrate-card {
  display: flex; flex-direction: column; align-items: center; gap: 2px;
  padding: 26px 40px 22px; border-radius: 18px;
  background: color-mix(in srgb, var(--surface) 88%, transparent);
  border: 1px solid var(--border); box-shadow: var(--shadow);
  backdrop-filter: blur(6px);
  animation: celebrate-pop .55s var(--ease-pop) both, celebrate-out .4s var(--ease) 2.6s both;
}
.celebrate-card img { width: 168px; height: 168px; animation: celebrate-bounce 1.6s var(--ease) .5s 2; }
.celebrate-card b { font: 700 20px var(--font-serif); color: var(--text); }
.celebrate-card span { font-size: 13px; color: var(--text-2); }
@keyframes celebrate-pop {
  from { opacity: 0; transform: scale(.55) translateY(40px); }
}
@keyframes celebrate-out {
  to { opacity: 0; transform: translateY(-16px) scale(.92); }
}
@keyframes celebrate-bounce {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-9px); }
}

@media (prefers-reduced-motion: reduce) {
  * { animation-duration: .001ms !important; transition-duration: .05ms !important; }
  .celebrate-card { animation: celebrate-pop .001ms both; }
}