:root {
  --paper: #fbfaf6;
  --ink: #171817;
  --muted: #5f625e;
  --soft: #f0ece4;
  --line: #d7cdbc;
  --panel: rgba(255, 255, 255, 0.84);
  --panel-strong: #ffffff;
  --accent: #0f6f68;
  --accent-deep: #084a45;
  --red: #a9432f;
  --gold: #9a6d19;
  --blue: #314f78;
  --violet: #67518e;
  --code: #191a17;
  --shadow: 0 18px 46px rgba(45, 36, 23, 0.09);
  --serif: Georgia, "Times New Roman", "Noto Serif SC", serif;
  --sans: ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, "Noto Sans SC", sans-serif;
  --mono: "SFMono-Regular", "Cascadia Mono", "Liberation Mono", Menlo, monospace;
  --toc-width: 15rem;
  --toc-gap: 2.5rem;
}

html[data-theme="dark"] {
  --paper: #101213;
  --ink: #f4efe6;
  --muted: #b9b2a8;
  --soft: #181c1d;
  --line: #343b3d;
  --panel: rgba(27, 30, 31, 0.92);
  --panel-strong: #222729;
  --accent: #51b8c8;
  --accent-deep: #9ee8f2;
  --red: #d66f5d;
  --gold: #d89b47;
  --blue: #82aee3;
  --violet: #a88bd8;
  --code: #0b0d0e;
  --shadow: 0 24px 70px rgba(0, 0, 0, 0.34);
  color-scheme: dark;
}

html[data-theme="dark"] body {
  background:
    linear-gradient(90deg, rgba(255, 255, 255, 0.035) 1px, transparent 1px) 0 0 / 42px 42px,
    linear-gradient(0deg, rgba(255, 255, 255, 0.028) 1px, transparent 1px) 0 0 / 42px 42px,
    var(--paper);
}

html[data-theme="dark"] .site-header {
  background: rgba(16, 18, 19, 0.92);
}

html[data-theme="dark"] .module-nav a,
html[data-theme="dark"] .page-footer a {
  color: var(--muted);
  background: rgba(255, 255, 255, 0.04);
}

html[data-theme="dark"] .module-nav a:first-child {
  color: #e8fbff;
  background: rgba(81, 184, 200, 0.12);
}

html[data-theme="dark"] .lecture-toc {
  background: rgba(16, 18, 19, 0.86);
}

html[data-theme="dark"] .lab-canvas,
html[data-theme="dark"] .attention-grid,
html[data-theme="dark"] .token-grid,
html[data-theme="dark"] .cache-visual,
html[data-theme="dark"] .pipeline-visual {
  background: var(--panel-strong);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  font-family: var(--sans);
  letter-spacing: 0;
  background:
    linear-gradient(90deg, rgba(23, 24, 23, 0.035) 1px, transparent 1px) 0 0 / 42px 42px,
    linear-gradient(0deg, rgba(23, 24, 23, 0.028) 1px, transparent 1px) 0 0 / 42px 42px,
    var(--paper);
}

a {
  color: inherit;
}

button,
input,
select {
  font: inherit;
}

canvas {
  display: block;
}

.skip-link {
  position: fixed;
  top: 0.75rem;
  left: 0.75rem;
  z-index: 60;
  width: 1px;
  height: 1px;
  padding: 0.55rem 0.75rem;
  overflow: hidden;
  color: #fff;
  text-decoration: none;
  clip: rect(0, 0, 0, 0);
  clip-path: inset(50%);
  background: var(--ink);
  border-radius: 4px;
}

.skip-link:focus {
  width: auto;
  height: auto;
  overflow: visible;
  clip: auto;
  clip-path: none;
}

.reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 80;
  width: 100%;
  height: 3px;
}

.reading-progress span {
  display: block;
  width: 0%;
  height: 100%;
  background: var(--accent);
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  padding: 0.85rem max(1rem, calc((100vw - 1040px) / 2));
  border-bottom: 1px solid var(--line);
  background: rgba(251, 250, 246, 0.94);
  backdrop-filter: blur(14px);
}

.brand,
.module-nav a,
.page-footer a {
  text-decoration: none;
}

.brand {
  font-family: var(--serif);
  font-weight: 800;
}

.module-nav {
  display: flex;
  align-items: center;
  gap: 0.45rem;
}

.module-nav a,
.page-footer a {
  padding: 0.42rem 0.62rem;
  color: var(--muted);
  font-size: 0.86rem;
  font-weight: 800;
  border: 1px solid var(--line);
  border-radius: 4px;
  background: rgba(255, 255, 255, 0.62);
}

.module-nav a:first-child {
  color: var(--accent-deep);
  background: rgba(15, 111, 104, 0.08);
}

.module-nav a:hover,
.module-nav a:focus-visible,
.page-footer a:hover,
.page-footer a:focus-visible {
  color: #fff;
  background: var(--accent);
  outline: none;
}

.lecture {
  width: min(100% - 2rem, 980px);
  margin: 0 auto;
  padding: 2rem 0 4rem;
}

.paper-header {
  padding: 3.4rem 0 2.3rem;
  border-bottom: 3px double var(--line);
}

.kicker {
  margin: 0 0 0.82rem;
  color: var(--accent-deep);
  font-family: var(--mono);
  font-size: 0.78rem;
  font-weight: 850;
  letter-spacing: 0;
  text-transform: uppercase;
}

.paper-header h1 {
  max-width: 900px;
  margin: 0;
  font-family: var(--serif);
  font-size: clamp(3rem, 7vw, 5.35rem);
  line-height: 1.02;
  letter-spacing: 0;
}

.subtitle {
  max-width: 820px;
  margin: 1.2rem 0 0;
  color: var(--ink);
  font-family: var(--serif);
  font-size: clamp(1.12rem, 2vw, 1.46rem);
  line-height: 1.48;
}

.chapter {
  padding: 4rem 0 0;
}

.chapter-header {
  margin-bottom: 1.35rem;
}

.chapter h2 {
  margin: 0;
  font-family: var(--serif);
  font-size: clamp(2rem, 4vw, 2.8rem);
  line-height: 1.12;
  letter-spacing: 0;
}

.chapter h3 {
  margin: 0;
  font-family: var(--serif);
  font-size: 1.34rem;
  line-height: 1.28;
}

.chapter p,
.chapter li {
  color: var(--muted);
  font-size: 1rem;
  line-height: 1.84;
  overflow-wrap: anywhere;
}

.chapter p {
  margin: 1rem 0 0;
}

.chapter-summary {
  max-width: 820px;
  color: var(--ink);
  font-family: var(--serif);
  font-size: 1.12rem;
}

.intuition-section,
.derivation-section,
.visual-example,
.algorithm-panel,
.judgement-card,
.misconception-card,
.warning-card,
.chapter-checkpoints,
.source-note,
.lever-grid,
.decision-grid {
  padding: 1.25rem;
  margin-top: 1rem;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 6px;
  box-shadow: var(--shadow);
}

.equation {
  position: relative;
  margin: 1rem 0 0;
  padding: 1rem 1.2rem;
  overflow-x: auto;
  background: var(--soft);
  border: 1px solid var(--line);
  border-left: 4px solid var(--accent);
  border-radius: 4px;
}

.equation mjx-container {
  max-width: 100%;
  overflow-x: auto;
  overflow-y: hidden;
}

.lever-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0.8rem;
}

.lever-grid article {
  min-height: 7rem;
  padding: 0.95rem;
  background: var(--panel-strong);
  border: 1px solid var(--line);
  border-radius: 4px;
}

.lever-grid strong,
.decision-grid strong {
  display: block;
  color: var(--ink);
}

.lever-grid span {
  display: block;
  margin-top: 0.55rem;
  color: var(--muted);
  line-height: 1.55;
}

.visual-example {
  display: grid;
  grid-template-columns: minmax(0, 0.55fr) minmax(0, 1fr);
  gap: 1rem;
  align-items: start;
}

.visual-copy p {
  margin-top: 0.65rem;
}

.lab-card {
  min-width: 0;
}

.lab-controls {
  margin-bottom: 0.85rem;
}

.lab-controls-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0.7rem;
}

.lab-controls-grid label {
  display: grid;
  gap: 0.38rem;
  min-width: 0;
  color: var(--ink);
  font-size: 0.82rem;
  font-weight: 850;
}

input[type="range"] {
  width: 100%;
  accent-color: var(--accent);
}

select {
  width: 100%;
  min-height: 2.05rem;
  padding: 0.3rem 0.45rem;
  color: var(--ink);
  background: var(--panel-strong);
  border: 1px solid var(--line);
  border-radius: 4px;
}

output {
  color: var(--accent-deep);
  font-family: var(--mono);
  font-size: 0.8rem;
}

.lab-canvas {
  width: 100%;
  height: auto;
  aspect-ratio: 2.5 / 1;
  background: #fffdf8;
  border: 1px solid var(--line);
  border-radius: 4px;
}

.timeline-scheduler {
  aspect-ratio: 2.2 / 1;
}

.lab-readout {
  padding: 0.65rem 0.8rem;
  margin-top: 0.75rem;
  color: var(--ink);
  font-family: var(--mono);
  font-size: 0.86rem;
  background: var(--soft);
  border-radius: 4px;
}

.bottleneck-bars,
.memory-bars {
  display: grid;
  gap: 0.65rem;
  margin-top: 0.85rem;
}

.bottleneck-bar,
.memory-bar {
  display: grid;
  grid-template-columns: minmax(7rem, 0.35fr) minmax(0, 1fr) minmax(4rem, auto);
  gap: 0.75rem;
  align-items: center;
}

.bottleneck-bar span,
.memory-bar span {
  color: var(--muted);
  font-size: 0.84rem;
  font-weight: 850;
}

.bottleneck-bar i,
.memory-bar i {
  display: block;
  width: var(--value, 50%);
  height: 0.76rem;
  background: var(--accent);
  border-radius: 999px;
  box-shadow: inset 0 0 0 1px rgba(0, 0, 0, 0.08);
}

.bottleneck-bar:nth-child(2) i,
.memory-bar:nth-child(2) i {
  background: var(--blue);
}

.bottleneck-bar:nth-child(3) i,
.memory-bar:nth-child(3) i {
  background: var(--gold);
}

.bottleneck-bar:nth-child(4) i,
.memory-bar:nth-child(4) i {
  background: var(--red);
}

.algorithm-panel {
  background: #fffdf8;
}

.panel-title {
  display: flex;
  gap: 1rem;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1rem;
}

.segmented {
  display: inline-flex;
  flex-wrap: wrap;
  gap: 0.35rem;
}

.segmented button {
  min-height: 2rem;
  padding: 0.38rem 0.62rem;
  color: var(--muted);
  font-size: 0.82rem;
  font-weight: 850;
  cursor: pointer;
  background: var(--soft);
  border: 1px solid var(--line);
  border-radius: 4px;
}

.segmented button.active,
.segmented button:hover,
.segmented button:focus-visible {
  color: #fff;
  background: var(--accent);
  outline: none;
}

.algorithm {
  max-width: 100%;
  min-height: 15rem;
  padding: 1rem;
  margin: 0;
  overflow-x: auto;
  color: #f8f0de;
  font-family: var(--mono);
  font-size: 0.82rem;
  line-height: 1.72;
  white-space: pre;
  background: var(--code);
  border-radius: 4px;
}

.judgement-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1rem;
  margin-top: 0.9rem;
}

.judgement-grid div {
  padding: 0.95rem;
  background: var(--soft);
  border-radius: 4px;
}

.judgement-grid strong {
  color: var(--ink);
}

.warning-card {
  border-left: 4px solid var(--red);
}

.warning-card h3 {
  color: var(--red);
}

.warning-card ul,
.misconception-card ul {
  padding-left: 1.2rem;
  margin: 0.75rem 0 0;
}

.timeline-roadmap {
  display: grid;
  grid-template-columns: repeat(7, minmax(160px, 1fr));
  gap: 0.5rem;
  align-items: stretch;
  padding: 1rem;
  margin-top: 1rem;
  overflow-x: auto;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 6px;
  box-shadow: var(--shadow);
}

.timeline-roadmap article {
  min-height: 13rem;
  padding: 0.9rem;
  background: var(--panel-strong);
  border: 1px solid var(--line);
  border-radius: 4px;
}

.timeline-roadmap time {
  display: block;
  color: var(--accent-deep);
  font-family: var(--mono);
  font-size: 0.82rem;
  font-weight: 900;
}

.timeline-roadmap strong {
  display: block;
  margin-top: 0.45rem;
  color: var(--ink);
  line-height: 1.35;
}

.timeline-roadmap p {
  margin-top: 0.55rem;
  font-size: 0.9rem;
  line-height: 1.62;
}

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

.decision-grid article {
  padding: 1rem;
  background: var(--panel-strong);
  border: 1px solid var(--line);
  border-radius: 4px;
}

.decision-grid h3 {
  font-size: 1.18rem;
}

.toc-toggle {
  position: fixed;
  right: 1rem;
  bottom: 1rem;
  z-index: 50;
  display: none;
  padding: 0.58rem 0.78rem;
  color: #fff;
  font-weight: 850;
  cursor: pointer;
  background: var(--accent);
  border: 0;
  border-radius: 4px;
}

.lecture-toc {
  position: fixed;
  top: 6rem;
  left: max(1rem, calc((100vw - 1360px) / 2));
  z-index: 20;
  width: var(--toc-width);
  max-height: calc(100vh - 7rem);
  padding: 1rem;
  overflow-y: auto;
  background: rgba(255, 255, 255, 0.78);
  border: 1px solid var(--line);
  border-radius: 6px;
  box-shadow: var(--shadow);
}

.lecture-toc p {
  margin: 0 0 0.6rem;
  color: var(--accent-deep);
  font-family: var(--mono);
  font-size: 0.78rem;
  font-weight: 900;
  text-transform: uppercase;
}

.lecture-toc nav {
  display: grid;
  gap: 0.2rem;
}

.lecture-toc a {
  padding: 0.42rem 0.5rem;
  color: var(--muted);
  font-size: 0.84rem;
  font-weight: 760;
  text-decoration: none;
  border-radius: 4px;
}

.lecture-toc a.active,
.lecture-toc a:hover,
.lecture-toc a:focus-visible {
  color: #fff;
  background: var(--accent);
  outline: none;
}

.page-footer {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  justify-content: center;
  width: min(100% - 2rem, 980px);
  padding: 2rem 0 3rem;
  margin: 0 auto;
  border-top: 1px solid var(--line);
}

@media (min-width: 1341px) {
  .lecture,
  .page-footer {
    width: min(calc(100vw - var(--toc-width) - var(--toc-gap) - 4rem), 980px);
    margin-left: calc(max(1rem, calc((100vw - 1360px) / 2)) + var(--toc-width) + var(--toc-gap));
    margin-right: auto;
  }
}

@media (max-width: 1340px) {
  .lecture-toc {
    display: none;
  }

  .toc-toggle {
    display: inline-flex;
  }

  .lecture-toc.open {
    display: block;
    top: auto;
    right: 1rem;
    bottom: 4rem;
    left: auto;
    width: min(22rem, calc(100vw - 2rem));
  }
}

@media (max-width: 860px) {
  .site-header,
  .module-nav,
  .panel-title,
  .visual-example {
    align-items: stretch;
  }

  .site-header,
  .panel-title {
    flex-direction: column;
  }

  .module-nav {
    flex-wrap: wrap;
  }

  .visual-example,
  .judgement-grid,
  .lab-controls-grid,
  .lever-grid,
  .decision-grid {
    grid-template-columns: 1fr;
  }

  .paper-header h1 {
    font-size: clamp(2.45rem, 12vw, 4rem);
  }

  .algorithm {
    font-size: 0.74rem;
  }

  .bottleneck-bar,
  .memory-bar {
    grid-template-columns: 1fr;
    gap: 0.35rem;
  }
}