:root {
  color-scheme: light;
  --brand: oklch(0.62 0.22 267);
  --brand-strong: oklch(0.52 0.24 267);
  --brand-soft: oklch(0.96 0.028 267);
  --ink: oklch(0.23 0.025 260);
  --muted: oklch(0.49 0.025 260);
  --subtle: oklch(0.68 0.02 260);
  --line: oklch(0.89 0.018 260);
  --line-strong: oklch(0.79 0.035 260);
  --paper: oklch(0.995 0.003 260);
  --surface: oklch(1 0 0);
  --surface-soft: oklch(0.975 0.01 260);
  --success: oklch(0.56 0.15 153);
  --success-soft: oklch(0.96 0.035 153);
  --warning: oklch(0.68 0.15 72);
  --warning-soft: oklch(0.97 0.04 80);
  --danger: oklch(0.58 0.19 25);
  --danger-soft: oklch(0.96 0.035 25);
  --code: oklch(0.27 0.035 260);
  --shadow: 0 1.25rem 3rem oklch(0.29 0.04 260 / 0.08);
  --radius: 1.1rem;
  --page: 72rem;
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --brand: oklch(0.75 0.15 264);
  --brand-strong: oklch(0.82 0.12 264);
  --brand-soft: oklch(0.28 0.07 264);
  --ink: oklch(0.94 0.012 260);
  --muted: oklch(0.73 0.022 260);
  --subtle: oklch(0.59 0.022 260);
  --line: oklch(0.34 0.025 260);
  --line-strong: oklch(0.45 0.035 260);
  --paper: oklch(0.18 0.02 260);
  --surface: oklch(0.22 0.022 260);
  --surface-soft: oklch(0.25 0.022 260);
  --success: oklch(0.75 0.12 153);
  --success-soft: oklch(0.29 0.055 153);
  --warning: oklch(0.82 0.12 82);
  --warning-soft: oklch(0.3 0.055 72);
  --danger: oklch(0.75 0.14 25);
  --danger-soft: oklch(0.29 0.06 25);
  --code: oklch(0.91 0.012 260);
  --shadow: 0 1.25rem 3rem oklch(0.05 0.02 260 / 0.26);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background:
    radial-gradient(circle at 85% -10%, oklch(0.9 0.08 264 / 0.28), transparent 30rem),
    var(--paper);
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  font-size: 1rem;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  color: var(--brand-strong);
  text-decoration-thickness: from-font;
  text-underline-offset: 0.18em;
  text-decoration-skip-ink: auto;
}

a:hover {
  color: var(--brand);
}

button,
summary,
a {
  -webkit-tap-highlight-color: transparent;
}

:focus-visible {
  outline: 0.18rem solid var(--brand);
  outline-offset: 0.2rem;
}

::selection {
  background: var(--brand);
  color: var(--surface);
}

.skip-link {
  position: fixed;
  inset-block-start: 0.5rem;
  inset-inline-start: 0.5rem;
  z-index: 100;
  transform: translateY(-180%);
  border-radius: 0.5rem;
  background: var(--ink);
  color: var(--surface);
  padding: 0.65rem 0.9rem;
}

.skip-link:focus {
  transform: translateY(0);
}

.container {
  width: min(calc(100% - 2rem), var(--page));
  margin-inline: auto;
}

.site-header {
  position: sticky;
  inset-block-start: 0;
  z-index: 30;
  border-block-end: 1px solid var(--line);
  background: color-mix(in oklch, var(--paper) 88%, transparent);
  backdrop-filter: blur(1rem);
}

.header-inner {
  min-height: 4.25rem;
  display: flex;
  align-items: center;
  gap: 1rem;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.65rem;
  min-height: 2.75rem;
  color: var(--ink);
  font-weight: 720;
  text-decoration: none;
  white-space: nowrap;
}

.brand img {
  inline-size: 2rem;
  block-size: 2rem;
}

.brand small {
  color: var(--muted);
  font-size: 0.76rem;
  font-weight: 560;
  letter-spacing: 0.01em;
}

.desktop-nav {
  margin-inline-start: auto;
  display: flex;
  align-items: center;
  gap: 0.1rem;
}

.desktop-nav a {
  min-height: 2.75rem;
  display: inline-flex;
  align-items: center;
  border-radius: 0.7rem;
  color: var(--muted);
  font-size: 0.88rem;
  font-weight: 620;
  padding-inline: 0.72rem;
  text-decoration: none;
}

.desktop-nav a:hover,
.desktop-nav a[aria-current="page"] {
  background: var(--brand-soft);
  color: var(--brand-strong);
}

.theme-toggle {
  min-inline-size: 2.75rem;
  min-block-size: 2.75rem;
  display: inline-grid;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 0.75rem;
  background: var(--surface);
  color: var(--ink);
  cursor: pointer;
  font: inherit;
}

.theme-toggle:hover {
  border-color: var(--line-strong);
  background: var(--surface-soft);
}

.theme-icon {
  font-size: 1.05rem;
  line-height: 1;
}

.mobile-nav {
  display: none;
  margin-inline-start: auto;
}

.mobile-nav summary {
  min-width: 2.75rem;
  min-height: 2.75rem;
  display: grid;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 0.75rem;
  background: var(--surface);
  cursor: pointer;
  list-style: none;
}

.mobile-nav summary::-webkit-details-marker {
  display: none;
}

.mobile-panel {
  position: absolute;
  inset-inline: 1rem;
  inset-block-start: 4rem;
  display: grid;
  gap: 0.25rem;
  border: 1px solid var(--line);
  border-radius: 1rem;
  background: var(--surface);
  box-shadow: var(--shadow);
  padding: 0.65rem;
}

.mobile-panel a {
  min-height: 2.75rem;
  display: flex;
  align-items: center;
  border-radius: 0.65rem;
  color: var(--ink);
  padding-inline: 0.8rem;
  text-decoration: none;
}

.mobile-panel a[aria-current="page"] {
  background: var(--brand-soft);
  color: var(--brand-strong);
}

.page-intro {
  padding-block: clamp(4rem, 9vw, 7.2rem) clamp(3rem, 7vw, 5.2rem);
}

.kicker,
.question-label,
.figure-label,
.evidence-label {
  color: var(--brand-strong);
  font-size: 0.76rem;
  font-weight: 760;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1,
h2,
h3,
p {
  margin-block-start: 0;
}

h1,
h2,
h3 {
  line-height: 1.15;
  text-wrap: balance;
}

h1 {
  max-width: 17ch;
  margin-block: 0.75rem 1.25rem;
  font-size: clamp(2.45rem, 6vw, 5rem);
  letter-spacing: -0.045em;
}

h2 {
  margin-block-end: 1rem;
  font-size: clamp(1.75rem, 3.8vw, 2.7rem);
  letter-spacing: -0.03em;
}

h3 {
  margin-block-end: 0.55rem;
  font-size: 1.08rem;
  letter-spacing: -0.012em;
}

.lead {
  max-width: 66ch;
  margin-block-end: 0;
  color: var(--muted);
  font-size: clamp(1.08rem, 2vw, 1.28rem);
  line-height: 1.7;
  text-wrap: pretty;
}

.lead strong,
.answer-lead strong {
  color: var(--ink);
}

.page-summary {
  max-width: 58rem;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
  margin-block-start: 2.2rem;
}

.summary-item {
  border-inline-start: 0.22rem solid var(--brand);
  padding-inline-start: 0.9rem;
}

.summary-item strong {
  display: block;
  margin-block-end: 0.2rem;
}

.summary-item span {
  color: var(--muted);
  font-size: 0.9rem;
}

.qa-section {
  scroll-margin-top: 5.5rem;
  border-block-start: 1px solid var(--line);
  padding-block: clamp(3.5rem, 8vw, 6.5rem);
}

.qa-heading {
  max-width: 54rem;
}

.answer-lead {
  max-width: 70ch;
  margin-block-end: 2rem;
  color: var(--muted);
  font-size: 1.08rem;
  line-height: 1.75;
}

.answer-lead code,
p code,
li code,
td code,
.code-tag {
  border: 1px solid var(--line);
  border-radius: 0.35rem;
  background: var(--surface-soft);
  color: var(--code);
  padding: 0.08em 0.34em;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  font-size: 0.9em;
  overflow-wrap: anywhere;
}

.visual {
  overflow: hidden;
  margin: 2rem 0;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  box-shadow: var(--shadow);
}

.visual-body {
  padding: clamp(1.2rem, 3vw, 2rem);
}

.visual figcaption {
  border-block-start: 1px solid var(--line);
  background: var(--surface-soft);
  color: var(--muted);
  padding: 0.85rem 1.2rem;
  font-size: 0.88rem;
}

.flow {
  display: flex;
  align-items: stretch;
  gap: 0.55rem;
  overflow-x: auto;
}

.flow.compact {
  justify-content: center;
}

.flow-node,
.state-node,
.layer,
.lane-cell,
.decision-node,
.role-node {
  min-width: 0;
  border: 1px solid var(--line);
  border-radius: 0.8rem;
  background: var(--surface-soft);
  padding: 0.9rem;
}

.flow-node {
  flex: 1 0 8.5rem;
  display: flex;
  flex-direction: column;
  justify-content: center;
  min-height: 6.7rem;
}

.flow-node strong,
.layer strong,
.lane-cell strong,
.role-node strong,
.decision-node strong {
  display: block;
  color: var(--ink);
}

.flow-node span,
.layer span,
.lane-cell span,
.role-node span,
.decision-node span {
  display: block;
  margin-block-start: 0.25rem;
  color: var(--muted);
  font-size: 0.82rem;
  line-height: 1.45;
}

.flow-node.accent,
.layer.accent,
.role-node.accent,
.state-node.accent {
  border-color: color-mix(in oklch, var(--brand) 52%, var(--line));
  background: var(--brand-soft);
}

.flow-arrow {
  flex: 0 0 2rem;
  display: grid;
  place-items: center;
  color: var(--brand);
  font-size: 1.4rem;
  font-weight: 760;
}

.module-map {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 0.8rem;
}

.module-link {
  min-height: 10rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  border: 1px solid var(--line);
  border-radius: 0.9rem;
  background: var(--surface-soft);
  color: var(--ink);
  padding: 1rem;
  text-decoration: none;
}

.module-link:hover {
  border-color: var(--brand);
  background: var(--brand-soft);
}

.module-link span {
  color: var(--muted);
  font-size: 0.86rem;
}

.module-link b {
  color: var(--brand-strong);
  font-size: 1.2rem;
}

.comparison {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.94rem;
}

.comparison th,
.comparison td {
  border-block-end: 1px solid var(--line);
  padding: 0.9rem 1rem;
  text-align: start;
  vertical-align: top;
}

.comparison th {
  background: var(--surface-soft);
  color: var(--ink);
  font-size: 0.78rem;
  letter-spacing: 0.04em;
}

.comparison tbody tr:last-child td {
  border-block-end: 0;
}

.comparison td:first-child {
  color: var(--ink);
  font-weight: 680;
}

.table-scroll {
  overflow-x: auto;
}

.trace-grid,
.two-col,
.three-col,
.role-grid {
  display: grid;
  gap: 1rem;
}

.role-grid + .role-grid {
  margin-block-start: 1rem;
}

.trace-grid,
.three-col {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

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

.trace,
.explain-block {
  border-block-start: 0.22rem solid var(--brand);
  padding-block-start: 0.9rem;
}

.trace p,
.explain-block p {
  margin-block-end: 0;
  color: var(--muted);
}

.timeline {
  display: grid;
  gap: 0;
}

.timeline-row {
  display: grid;
  grid-template-columns: 7.5rem 1fr;
  gap: 1rem;
  position: relative;
}

.timeline-row:not(:last-child)::before {
  content: "";
  position: absolute;
  inset-block-start: 2.1rem;
  inset-block-end: -0.2rem;
  inset-inline-start: calc(7.5rem + 0.34rem);
  inline-size: 2px;
  background: var(--line-strong);
}

.timeline-time {
  color: var(--brand-strong);
  font-family: "SFMono-Regular", Consolas, monospace;
  font-size: 0.82rem;
  font-weight: 700;
  text-align: end;
  padding-block-start: 0.65rem;
}

.timeline-content {
  position: relative;
  padding: 0.55rem 0 1.45rem 1.5rem;
}

.timeline-content::before {
  content: "";
  position: absolute;
  inset-block-start: 0.9rem;
  inset-inline-start: -0.18rem;
  inline-size: 0.72rem;
  block-size: 0.72rem;
  border: 0.16rem solid var(--surface);
  border-radius: 50%;
  background: var(--brand);
  box-shadow: 0 0 0 1px var(--line-strong);
}

.timeline-content p {
  margin-block-end: 0;
  color: var(--muted);
}

.lane-diagram {
  display: grid;
  grid-template-columns: 8rem repeat(3, minmax(0, 1fr));
  gap: 0.45rem;
}

.lane-label {
  display: flex;
  align-items: center;
  color: var(--muted);
  font-size: 0.82rem;
  font-weight: 700;
}

.lane-cell {
  min-height: 5.5rem;
}

.lane-cell.success {
  border-color: color-mix(in oklch, var(--success) 44%, var(--line));
  background: var(--success-soft);
}

.lane-cell.warning {
  border-color: color-mix(in oklch, var(--warning) 44%, var(--line));
  background: var(--warning-soft);
}

.state-flow {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.state-node {
  min-width: 9rem;
  text-align: center;
}

.state-node small {
  display: block;
  margin-block-start: 0.3rem;
  color: var(--muted);
}

.state-arrow {
  color: var(--brand);
  font-weight: 760;
}

.layer-stack {
  display: grid;
  gap: 0.6rem;
  max-width: 48rem;
  margin-inline: auto;
}

.layer {
  display: grid;
  grid-template-columns: 9rem 1fr;
  align-items: center;
  gap: 1rem;
}

.layer > span {
  margin: 0;
}

.log-pipeline {
  display: grid;
  grid-template-columns: 1fr 2rem 1fr 2rem 1fr;
  align-items: center;
  gap: 0.5rem;
}

.log-column {
  display: grid;
  gap: 0.5rem;
}

.log-item {
  border: 1px solid var(--line);
  border-radius: 0.65rem;
  background: var(--surface-soft);
  padding: 0.65rem 0.75rem;
  font-family: "SFMono-Regular", Consolas, monospace;
  font-size: 0.8rem;
}

.log-item.muted {
  color: var(--subtle);
  text-decoration: line-through;
}

.log-arrow {
  color: var(--brand);
  font-size: 1.35rem;
  text-align: center;
}

.role-grid {
  grid-template-columns: 1fr auto 1fr auto 1fr;
  align-items: stretch;
}

.role-node {
  min-height: 8rem;
}

.role-arrow {
  display: grid;
  place-items: center;
  color: var(--brand);
  font-weight: 800;
}

.pipeline-list {
  counter-reset: pipeline;
  display: grid;
  gap: 0.55rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

.pipeline-list li {
  counter-increment: pipeline;
  display: grid;
  grid-template-columns: 2.1rem 1fr;
  gap: 0.75rem;
  align-items: start;
  border-block-end: 1px solid var(--line);
  padding-block: 0.65rem 0.9rem;
}

.pipeline-list li:last-child {
  border-block-end: 0;
}

.pipeline-list li::before {
  content: counter(pipeline);
  display: grid;
  place-items: center;
  inline-size: 2rem;
  block-size: 2rem;
  border-radius: 50%;
  background: var(--brand-soft);
  color: var(--brand-strong);
  font-size: 0.8rem;
  font-weight: 760;
}

.pipeline-list strong {
  display: block;
}

.pipeline-list span {
  color: var(--muted);
  font-size: 0.9rem;
}

.barrier {
  margin-block: 0.8rem;
  border: 1px dashed var(--brand);
  border-radius: 0.65rem;
  background: var(--brand-soft);
  color: var(--brand-strong);
  padding: 0.6rem 0.8rem;
  text-align: center;
  font-size: 0.82rem;
  font-weight: 700;
}

.callout {
  margin-block: 1.5rem;
  border-inline-start: 0.25rem solid var(--brand);
  border-radius: 0 0.8rem 0.8rem 0;
  background: var(--brand-soft);
  padding: 1rem 1.1rem;
}

.callout.warning {
  border-inline-start-color: var(--warning);
  background: var(--warning-soft);
}

.callout.danger {
  border-inline-start-color: var(--danger);
  background: var(--danger-soft);
}

.callout p:last-child,
.callout ul:last-child {
  margin-block-end: 0;
}

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

.decision-node {
  min-height: 7.4rem;
}

.decision-node.root {
  grid-column: 1 / -1;
  max-width: 28rem;
  min-height: auto;
  margin-inline: auto;
  border-color: var(--brand);
  background: var(--brand-soft);
  text-align: center;
}

.decision-node.yes {
  border-block-start: 0.22rem solid var(--success);
}

.decision-node.no {
  border-block-start: 0.22rem solid var(--warning);
}

.before-after {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 1rem;
}

.surface-list {
  display: grid;
  gap: 0.45rem;
  border: 1px solid var(--line);
  border-radius: 0.8rem;
  background: var(--surface-soft);
  padding: 0.8rem;
}

.surface-list span {
  border-radius: 0.5rem;
  background: var(--surface);
  padding: 0.55rem 0.7rem;
  font-size: 0.86rem;
}

.surface-list span.shadowed {
  color: var(--subtle);
  text-decoration: line-through;
}

.source-evidence {
  margin-block-start: 2rem;
  border-block-start: 1px solid var(--line);
  padding-block-start: 1.2rem;
}

.source-evidence ul {
  display: flex;
  flex-wrap: wrap;
  gap: 0.55rem 1.1rem;
  margin: 0.55rem 0 0;
  padding: 0;
  list-style: none;
}

.source-evidence a {
  font-size: 0.88rem;
  font-weight: 650;
}

.next-pages {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1rem;
  border-block-start: 1px solid var(--line);
  padding-block: 2.5rem 4rem;
}

.next-page {
  min-height: 6.5rem;
  display: flex;
  flex-direction: column;
  justify-content: center;
  border: 1px solid var(--line);
  border-radius: 0.9rem;
  background: var(--surface);
  color: var(--ink);
  padding: 1rem 1.2rem;
  text-decoration: none;
}

.next-page:last-child {
  text-align: end;
}

.next-page span {
  color: var(--muted);
  font-size: 0.78rem;
}

.next-page strong {
  margin-block-start: 0.2rem;
  color: var(--brand-strong);
}

.site-footer {
  border-block-start: 1px solid var(--line);
  color: var(--muted);
  padding-block: 1.4rem 2.2rem;
  font-size: 0.84rem;
}

.site-footer .container {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
}

.site-footer p {
  margin: 0;
}

.sr-only {
  position: absolute;
  inline-size: 1px;
  block-size: 1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  clip-path: inset(50%);
}

@media (max-width: 64rem) {
  .desktop-nav {
    display: none;
  }

  .mobile-nav {
    display: block;
  }

  .header-inner > .theme-toggle {
    margin-inline-start: 0;
  }

  .module-map {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .lane-diagram {
    grid-template-columns: 7rem repeat(3, minmax(10rem, 1fr));
    overflow-x: auto;
  }
}

@media (max-width: 46rem) {
  .container {
    width: min(calc(100% - 1.25rem), var(--page));
  }

  .brand small {
    display: none;
  }

  .page-summary,
  .trace-grid,
  .two-col,
  .three-col,
  .decision-tree {
    grid-template-columns: 1fr;
  }

  .module-map {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .module-link {
    min-height: 8.5rem;
  }

  .flow,
  .flow.compact,
  .log-pipeline,
  .role-grid,
  .before-after {
    grid-template-columns: 1fr;
  }

  .flow,
  .flow.compact {
    flex-direction: column;
    overflow-x: visible;
  }

  .flow-node,
  .flow-arrow {
    flex: auto;
  }

  .flow-arrow,
  .log-arrow,
  .role-arrow {
    transform: rotate(90deg);
    min-height: 1.5rem;
  }

  .layer {
    grid-template-columns: 1fr;
    gap: 0.15rem;
  }

  .timeline-row {
    grid-template-columns: 4.2rem 1fr;
  }

  .timeline-row:not(:last-child)::before {
    inset-inline-start: calc(4.2rem + 0.34rem);
  }

  .comparison th,
  .comparison td {
    min-width: 9.5rem;
    padding: 0.75rem;
  }

  .next-pages {
    grid-template-columns: 1fr;
  }

  .next-page:last-child {
    text-align: start;
  }

  .site-footer .container {
    display: block;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
}

@media (forced-colors: active) {
  :focus-visible {
    outline-color: Highlight;
  }
}

@media print {
  .site-header,
  .skip-link,
  .next-pages,
  .site-footer {
    display: none;
  }

  body {
    background: white;
    color: black;
  }

  .qa-section,
  .visual {
    break-inside: avoid;
  }

  .visual {
    box-shadow: none;
  }

  a {
    color: black;
  }
}