:root {
  color-scheme: light;
  --bg: #f6f8fb;
  --paper: #ffffff;
  --ink: #1f252b;
  --muted: #66707a;
  --line: #dfe5ec;
  --teal: #168f84;
  --coral: #d95d59;
  --blue: #3f63b8;
  --gold: #c88d22;
  --mint: #dff4ee;
  --rose: #ffe7e4;
  --sky: #e8f0ff;
  --shadow: 0 18px 45px rgba(30, 40, 55, 0.09);
}

:root.dark {
  color-scheme: dark;
  --bg: #151719;
  --paper: #202427;
  --ink: #eff3f5;
  --muted: #abb6bd;
  --line: #363f45;
  --teal: #65d0c6;
  --coral: #ff8b83;
  --blue: #9bb8ff;
  --gold: #f1c36f;
  --mint: #203a35;
  --rose: #462827;
  --sky: #263249;
  --shadow: 0 18px 45px rgba(0, 0, 0, 0.28);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: linear-gradient(180deg, rgba(22, 143, 132, 0.06), transparent 360px), var(--bg);
  color: var(--ink);
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  line-height: 1.68;
  letter-spacing: 0;
}

a {
  color: inherit;
  text-decoration: none;
}

img {
  display: block;
  max-width: 100%;
}

code {
  display: block;
  width: 100%;
  overflow-x: auto;
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: color-mix(in srgb, var(--bg) 68%, var(--paper));
  color: var(--blue);
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  font-size: 0.92rem;
  line-height: 1.5;
  white-space: nowrap;
}

button,
input {
  font: inherit;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 68px;
  padding: 12px clamp(16px, 4vw, 44px);
  border-bottom: 1px solid color-mix(in srgb, var(--line) 78%, transparent);
  background: color-mix(in srgb, var(--paper) 88%, transparent);
  backdrop-filter: blur(16px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  font-weight: 760;
}

.brand-mark {
  display: inline-grid;
  min-width: 76px;
  height: 36px;
  place-items: center;
  border-radius: 6px;
  background: var(--ink);
  color: var(--paper);
  font-size: 0.88rem;
}

.toolbar {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 10px;
}

.search {
  display: flex;
  align-items: center;
  flex: 1 1 260px;
  width: min(360px, 40vw);
  min-height: 42px;
  padding: 0 12px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--paper);
  color: var(--muted);
}

.search input {
  width: 100%;
  min-width: 0;
  border: 0;
  outline: 0;
  background: transparent;
  color: var(--ink);
}

.icon-button {
  width: 42px;
  height: 42px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--paper);
  color: var(--ink);
  cursor: pointer;
}

.home-pill {
  display: inline-grid;
  min-height: 42px;
  place-items: center;
  padding: 0 12px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--paper);
  color: var(--muted);
  font-weight: 720;
}

.home-pill:hover {
  background: var(--mint);
  color: var(--ink);
}

.page-shell {
  display: grid;
  grid-template-columns: 248px minmax(0, 1fr);
  gap: 28px;
  width: min(1440px, 100%);
  margin: 0 auto;
  padding: 28px clamp(16px, 4vw, 44px) 72px;
}

.side-nav {
  position: sticky;
  top: 92px;
  align-self: start;
  display: grid;
  gap: 18px;
  max-height: calc(100vh - 112px);
  overflow: auto;
}

.side-nav nav {
  display: grid;
  gap: 4px;
  padding: 8px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--paper);
  box-shadow: var(--shadow);
}

.side-nav a {
  padding: 9px 10px;
  border-radius: 6px;
  color: var(--muted);
  font-size: 0.95rem;
}

.side-nav a:hover,
.side-nav a.active {
  background: var(--mint);
  color: var(--ink);
}

.progress-card {
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--paper);
  color: var(--muted);
  font-size: 0.9rem;
}

.progress-track {
  height: 8px;
  margin-top: 10px;
  overflow: hidden;
  border-radius: 99px;
  background: color-mix(in srgb, var(--line) 55%, transparent);
}

#progressBar {
  width: 0;
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--teal), var(--coral));
}

main {
  display: grid;
  gap: 24px;
  min-width: 0;
}

.panel,
.section {
  min-width: 0;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--paper);
  box-shadow: var(--shadow);
}

.hero > *,
.section > *,
figure,
.compare-table,
.mask-demo {
  min-width: 0;
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1.3fr) minmax(320px, 0.7fr);
  gap: 28px;
  min-height: 460px;
  padding: clamp(24px, 5vw, 54px);
  overflow: hidden;
}

.hero h1 {
  max-width: 850px;
  margin: 0;
  font-size: 3.45rem;
  line-height: 1.12;
  letter-spacing: 0;
}

.lead {
  max-width: 760px;
  margin: 24px 0 0;
  color: var(--muted);
  font-size: 1.1rem;
}

.source-line {
  max-width: 760px;
  margin: 16px 0 0;
  color: var(--muted);
  font-size: 0.94rem;
}

.source-line a {
  color: var(--teal);
  font-weight: 720;
}

.eyebrow {
  margin: 0 0 8px;
  color: var(--teal);
  font-size: 0.78rem;
  font-weight: 780;
  letter-spacing: 0;
  text-transform: uppercase;
}

.hero-visual {
  position: relative;
  display: grid;
  align-content: center;
  gap: 22px;
  min-height: 310px;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: linear-gradient(135deg, color-mix(in srgb, var(--rose) 45%, var(--paper)), color-mix(in srgb, var(--sky) 45%, var(--paper)));
}

.flow-strip {
  display: grid;
  grid-template-columns: 1fr 44px 1fr 44px 1fr;
  align-items: center;
  gap: 8px;
}

.flow-strip span {
  display: grid;
  min-height: 68px;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--paper);
  color: var(--ink);
  font-weight: 760;
}

.flow-strip i {
  position: relative;
  height: 2px;
  background: var(--teal);
}

.flow-strip i::after {
  position: absolute;
  right: -2px;
  top: -5px;
  width: 0;
  height: 0;
  border-left: 10px solid var(--teal);
  border-top: 6px solid transparent;
  border-bottom: 6px solid transparent;
  content: "";
}

.mini-particles {
  position: relative;
  height: 120px;
  border: 1px dashed color-mix(in srgb, var(--line) 80%, transparent);
  border-radius: 8px;
  background: color-mix(in srgb, var(--bg) 70%, var(--paper));
}

.mini-particles b {
  position: absolute;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--coral);
  box-shadow: 0 0 0 5px color-mix(in srgb, var(--coral) 18%, transparent);
}

.mini-particles b:nth-child(1) { left: 10%; top: 22%; }
.mini-particles b:nth-child(2) { left: 18%; top: 66%; background: var(--gold); }
.mini-particles b:nth-child(3) { left: 32%; top: 38%; background: var(--teal); }
.mini-particles b:nth-child(4) { left: 45%; top: 72%; }
.mini-particles b:nth-child(5) { left: 58%; top: 28%; background: var(--blue); }
.mini-particles b:nth-child(6) { left: 70%; top: 56%; background: var(--teal); }
.mini-particles b:nth-child(7) { left: 82%; top: 32%; background: var(--gold); }
.mini-particles b:nth-child(8) { left: 88%; top: 78%; background: var(--blue); }

.hero-visual p {
  margin: 0;
  color: var(--muted);
}

.section {
  scroll-margin-top: 88px;
  padding: clamp(22px, 4vw, 42px);
}

.section-head {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 20px;
  margin-bottom: 22px;
}

.section h2 {
  margin: 0;
  font-size: 2.25rem;
  line-height: 1.22;
  letter-spacing: 0;
}

.section h3,
.hero h3 {
  margin: 0 0 10px;
  font-size: 1.12rem;
  line-height: 1.36;
}

.section p {
  margin: 0;
}

.math {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  color: var(--blue);
}

.map-grid {
  display: grid;
  grid-template-columns: repeat(5, minmax(150px, 1fr));
  gap: 12px;
}

.map-card,
.note-card,
.explain,
.concept-stack article,
.case-card,
.cheatsheet article,
.glossary-grid article,
.algorithm-card,
.callout {
  min-width: 0;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--paper);
}

.map-card {
  min-height: 210px;
  padding: 18px;
}

.num {
  display: inline-grid;
  width: 42px;
  height: 32px;
  place-items: center;
  margin-bottom: 18px;
  border-radius: 6px;
  background: var(--sky);
  color: var(--blue);
  font-weight: 760;
}

.map-card p,
.triad p,
.note-card,
.explain,
.concept-stack p,
.case-card p,
.glossary-grid span,
figcaption {
  color: var(--muted);
}

.triad {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin-top: 14px;
}

.triad div {
  min-height: 142px;
  padding: 18px;
  border-left: 4px solid var(--teal);
  border-radius: 8px;
  background: var(--mint);
}

.triad div:nth-child(2) {
  border-left-color: var(--coral);
  background: var(--rose);
}

.triad div:nth-child(3) {
  border-left-color: var(--blue);
  background: var(--sky);
}

.two-col {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}

.explain,
.note-card {
  padding: 20px;
}

.explain > * + *,
.note-card > * + *,
.algorithm-card > * + *,
.callout > * + * {
  margin-top: 12px;
}

.note-card ul {
  margin: 0;
  padding-left: 20px;
}

.formula-card {
  display: grid;
  gap: 8px;
  padding: 14px;
  border-radius: 8px;
  background: var(--sky);
}

.formula-card p {
  color: var(--ink);
}

.accent {
  background: color-mix(in srgb, var(--mint) 62%, var(--paper));
}

.image-row {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
  margin-bottom: 18px;
}

figure {
  margin: 0;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--paper);
}

figure img {
  width: 100%;
  height: 260px;
  object-fit: contain;
  background: #fff;
}

figcaption {
  padding: 12px 14px;
  border-top: 1px solid var(--line);
  font-size: 0.92rem;
}

.wide-figure {
  margin: 0 0 18px;
}

.wide-figure img {
  height: auto;
  max-height: 520px;
}

.compare-table {
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 8px;
}

.compare-table .row {
  display: grid;
  grid-template-columns: 0.8fr 1.25fr 1.25fr;
}

.compare-table .row + .row {
  border-top: 1px solid var(--line);
}

.compare-table span {
  min-width: 0;
  padding: 14px;
}

.compare-table span + span {
  border-left: 1px solid var(--line);
}

.compare-table .head {
  background: var(--ink);
  color: var(--paper);
  font-weight: 760;
}

.concept-stack {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
  margin-bottom: 16px;
}

.concept-stack article {
  min-height: 210px;
  padding: 18px;
}

.algorithm-card,
.callout {
  margin-top: 16px;
  padding: 20px;
  background: color-mix(in srgb, var(--rose) 48%, var(--paper));
}

.score-images figure img {
  height: 330px;
}

.gallery-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
  margin: 16px 0;
}

.gallery-grid figure img {
  height: 360px;
}

.case-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
}

.case-card {
  min-height: 150px;
  padding: 18px;
  background: color-mix(in srgb, var(--sky) 54%, var(--paper));
}

.mask-demo {
  display: grid;
  gap: 10px;
  margin-top: 16px;
  padding: 16px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: color-mix(in srgb, var(--bg) 64%, var(--paper));
}

.mask-demo div {
  display: grid;
  grid-template-columns: 74px repeat(5, minmax(72px, 1fr));
  gap: 8px;
  align-items: center;
}

.mask-demo span,
.mask-demo b {
  display: grid;
  min-height: 42px;
  place-items: center;
  border-radius: 6px;
  font-size: 0.94rem;
}

.mask-demo span {
  color: var(--muted);
}

.mask-demo b {
  border: 1px solid var(--line);
  background: var(--paper);
  color: var(--ink);
}

.cheatsheet {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 12px;
}

.cheatsheet article {
  min-height: 168px;
  padding: 16px;
}

.cheatsheet code + code {
  margin-top: 8px;
}

.glossary-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
}

.glossary-grid article {
  display: grid;
  gap: 8px;
  min-height: 118px;
  padding: 16px;
}

.glossary-grid b {
  color: var(--teal);
}

.empty-state {
  position: fixed;
  right: 24px;
  bottom: 24px;
  max-width: 360px;
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--paper);
  box-shadow: var(--shadow);
  color: var(--muted);
}

.is-hidden {
  display: none !important;
}

.highlight {
  outline: 3px solid color-mix(in srgb, var(--gold) 68%, transparent);
  outline-offset: 3px;
}

@media (max-width: 1120px) {
  .page-shell {
    grid-template-columns: 1fr;
  }

  .side-nav {
    position: static;
    max-height: none;
  }

  .side-nav nav {
    grid-template-columns: repeat(5, minmax(120px, 1fr));
  }

  .hero,
  .map-grid,
  .concept-stack,
  .cheatsheet,
  .glossary-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .hero h1 {
    font-size: 2.8rem;
  }
}

@media (max-width: 780px) {
  .topbar {
    align-items: stretch;
    flex-direction: column;
    gap: 12px;
  }

  .toolbar,
  .search {
    width: 100%;
  }

  .toolbar {
    align-items: stretch;
  }

  .home-pill,
  .icon-button {
    flex: 0 0 auto;
  }

  .page-shell {
    padding-top: 18px;
  }

  .side-nav nav,
  .hero,
  .map-grid,
  .triad,
  .two-col,
  .image-row,
  .concept-stack,
  .gallery-grid,
  .case-grid,
  .cheatsheet,
  .glossary-grid {
    grid-template-columns: 1fr;
  }

  .hero {
    min-height: auto;
  }

  .hero h1 {
    font-size: 2rem;
  }

  .section h2 {
    font-size: 1.65rem;
  }

  .section-head {
    display: block;
  }

  .compare-table {
    overflow: hidden;
  }

  .compare-table .row {
    grid-template-columns: 1fr;
    min-width: 0;
  }

  .compare-table span + span {
    border-left: 0;
    border-top: 1px solid var(--line);
  }

  .mask-demo {
    overflow: hidden;
  }

  .mask-demo div {
    grid-template-columns: 58px repeat(5, minmax(0, 1fr));
    min-width: 0;
    gap: 5px;
  }

  .mask-demo span,
  .mask-demo b {
    min-height: 36px;
    font-size: 0.78rem;
  }

  figure img,
  .score-images figure img,
  .gallery-grid figure img {
    height: auto;
    max-height: 420px;
  }
}