:root {
  color-scheme: dark;
  --bg: oklch(16% 0.018 250);
  --panel: oklch(20% 0.018 250);
  --panel-2: oklch(24% 0.018 250);
  --panel-3: oklch(29% 0.018 250);
  --line: oklch(34% 0.018 250);
  --line-strong: oklch(43% 0.025 250);
  --text: oklch(93% 0.012 250);
  --muted: oklch(74% 0.018 250);
  --dim: oklch(62% 0.018 250);
  --primary: oklch(78% 0.17 75);
  --primary-ink: oklch(20% 0.04 70);
  --info: oklch(75% 0.12 220);
  --success: oklch(74% 0.15 155);
  --danger: oklch(70% 0.17 25);
  --warning: oklch(78% 0.15 70);
  --code: oklch(14% 0.015 250);
  --space-1: .25rem;
  --space-2: .5rem;
  --space-3: .75rem;
  --space-4: 1rem;
  --space-5: 1.5rem;
  --space-6: 2rem;
  --space-7: 3rem;
  --radius: .625rem;
  --shadow: 0 .5rem 1.25rem oklch(8% 0.015 250 / .28);
}

* {
  box-sizing: border-box;
}

html {
  font-family: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 16px;
  line-height: 1.65;
  background: var(--bg);
  color: var(--text);
  font-kerning: normal;
}

body {
  margin: 0;
  min-height: 100vh;
  background:
    radial-gradient(circle at 20% 0%, oklch(28% 0.045 250 / .6), transparent 32rem),
    linear-gradient(180deg, oklch(17% 0.02 250), var(--bg) 18rem);
}

a {
  color: var(--info);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
  text-underline-offset: .2em;
}

button,
input {
  font: inherit;
}

:focus-visible {
  outline: .16rem solid var(--info);
  outline-offset: .18rem;
}

.app-shell {
  display: grid;
  grid-template-columns: 18rem minmax(0, 1fr);
  min-height: 100vh;
}

.sidebar {
  position: sticky;
  top: 0;
  height: 100vh;
  overflow: auto;
  border-right: 1px solid var(--line);
  background: oklch(18% 0.018 250 / .96);
  padding: var(--space-5) var(--space-4);
}

.brand {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  margin-bottom: var(--space-5);
}

.brand__title {
  color: var(--primary);
  font-size: .95rem;
  font-weight: 750;
  letter-spacing: .04em;
  text-transform: uppercase;
}

.brand__subtitle {
  color: var(--muted);
  font-size: .875rem;
  line-height: 1.45;
}

.progress-summary {
  display: grid;
  gap: var(--space-2);
  padding: var(--space-3);
  margin-bottom: var(--space-5);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
}

.progress-summary__row {
  display: flex;
  justify-content: space-between;
  gap: var(--space-3);
  color: var(--muted);
  font-size: .82rem;
}

.progress-track {
  height: .45rem;
  overflow: hidden;
  border-radius: 999px;
  background: var(--panel-3);
}

.progress-fill {
  display: block;
  width: 100%;
  height: 100%;
  border-radius: inherit;
  background: var(--primary);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 180ms ease-out;
}

.nav-group {
  display: grid;
  gap: var(--space-1);
  margin-bottom: var(--space-5);
}

.nav-label {
  margin: 0 0 var(--space-2);
  color: var(--dim);
  font-size: .75rem;
  font-weight: 700;
  letter-spacing: .08em;
  text-transform: uppercase;
}

.nav-link {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 2.5rem;
  padding: .55rem .65rem;
  border: 1px solid transparent;
  border-radius: .5rem;
  color: var(--muted);
  font-size: .9rem;
}

.nav-link:hover {
  background: var(--panel);
  color: var(--text);
  text-decoration: none;
}

.nav-link[aria-current="page"] {
  border-color: oklch(78% 0.17 75 / .55);
  background: oklch(78% 0.17 75 / .12);
  color: var(--primary);
}

.main {
  min-width: 0;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 2;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  min-height: 4rem;
  padding: 0 var(--space-6);
  border-bottom: 1px solid var(--line);
  background: oklch(16% 0.018 250 / .88);
  backdrop-filter: blur(14px);
}

.breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  color: var(--dim);
  font-size: .86rem;
}

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

.page {
  width: min(100%, 74rem);
  margin: 0 auto;
  padding: var(--space-7) var(--space-6);
}

.page--wide {
  width: min(100%, 92rem);
}

.page--lesson {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 18rem;
  align-items: start;
  gap: var(--space-6);
}

.content {
  min-width: 0;
}

.content h1,
.content h2,
.content h3 {
  color: var(--text);
  line-height: 1.2;
  text-wrap: balance;
}

.content h1 {
  margin: 0 0 var(--space-4);
  font-size: 2.25rem;
  letter-spacing: -.02em;
}

.content h2 {
  margin: var(--space-7) 0 var(--space-3);
  font-size: 1.45rem;
}

.content h3 {
  margin: var(--space-5) 0 var(--space-2);
  font-size: 1.1rem;
}

.lead {
  max-width: 68ch;
  margin: 0 0 var(--space-5);
  color: var(--muted);
  font-size: 1.05rem;
  text-wrap: pretty;
}

.prose {
  max-width: 72ch;
}

.prose p,
.prose li {
  color: var(--text);
  text-wrap: pretty;
}

.prose p {
  margin: 0 0 var(--space-4);
}

.prose ul,
.prose ol {
  margin: 0 0 var(--space-4);
  padding-left: 1.35rem;
}

.prose li + li {
  margin-top: .35rem;
}

.muted {
  color: var(--muted);
}

.meta-row,
.pager {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
  align-items: center;
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: .4rem;
  min-height: 1.75rem;
  padding: .2rem .6rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--muted);
  background: var(--panel);
  font-size: .8rem;
  font-weight: 650;
}

.badge--info {
  border-color: oklch(75% 0.12 220 / .45);
  color: var(--info);
}

.badge--success {
  border-color: oklch(74% 0.15 155 / .45);
  color: var(--success);
}

.badge--warning {
  border-color: oklch(78% 0.15 70 / .5);
  color: var(--warning);
}

.section-panel,
.lesson-list,
.aside-panel,
.callout,
.quiz-question {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: oklch(20% 0.018 250 / .78);
}

.section-panel {
  padding: var(--space-5);
}

.section-panel > h2:first-child,
.section-panel > h3:first-child {
  margin-top: 0;
}

.section-panel + .section-panel {
  margin-top: var(--space-4);
}

.lesson-list {
  display: grid;
  overflow: hidden;
}

.lesson-item {
  display: grid;
  grid-template-columns: 7rem minmax(0, 1fr) auto;
  gap: var(--space-4);
  align-items: center;
  padding: var(--space-4);
  border-bottom: 1px solid var(--line);
}

.lesson-item:last-child {
  border-bottom: 0;
}

.lesson-item:hover {
  background: oklch(24% 0.018 250 / .72);
  text-decoration: none;
}

.lesson-item__type {
  color: var(--dim);
  font-size: .78rem;
  font-weight: 750;
  letter-spacing: .06em;
  text-transform: uppercase;
}

.lesson-item__title {
  display: block;
  color: var(--text);
  font-weight: 700;
}

.lesson-item__desc {
  display: block;
  margin-top: .15rem;
  color: var(--muted);
  font-size: .9rem;
}

.summary-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(13rem, 1fr));
  gap: var(--space-4);
  margin: var(--space-5) 0;
}

.summary-card {
  display: grid;
  gap: var(--space-2);
  padding: var(--space-4);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: oklch(22% 0.018 250 / .72);
}

.summary-card__label,
.step-check__label {
  color: var(--dim);
  font-size: .74rem;
  font-weight: 750;
  letter-spacing: .06em;
  text-transform: uppercase;
}

.summary-card strong {
  color: var(--text);
  line-height: 1.25;
}

.summary-card span {
  color: var(--muted);
  font-size: .9rem;
  line-height: 1.45;
}

.step-check {
  display: grid;
  gap: var(--space-3);
  margin: var(--space-5) 0;
  padding: var(--space-4);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
}

.step-check ol {
  display: grid;
  gap: var(--space-2);
  margin: 0;
  padding-left: 1.2rem;
}

.step-check li::marker {
  color: var(--primary);
  font-weight: 800;
}

.aside {
  position: sticky;
  top: 5.25rem;
  display: grid;
  gap: var(--space-4);
}

.aside-panel {
  padding: var(--space-4);
}

.aside-panel h2,
.aside-panel h3 {
  margin: 0 0 var(--space-3);
  font-size: .95rem;
}

.aside-panel ul,
.aside-panel ol {
  margin: 0;
  padding-left: 1.1rem;
  color: var(--muted);
  font-size: .88rem;
}

.aside-panel li + li {
  margin-top: .35rem;
}

.check-row {
  display: flex;
  align-items: flex-start;
  gap: var(--space-2);
  color: var(--muted);
  font-size: .92rem;
}

.check-row input {
  width: 1rem;
  height: 1rem;
  margin-top: .25rem;
  accent-color: var(--primary);
}

.callout {
  padding: var(--space-4);
  margin: var(--space-5) 0;
}

.callout strong {
  color: var(--primary);
}

.callout--warning {
  border-color: oklch(78% 0.15 70 / .45);
  background: oklch(78% 0.15 70 / .08);
}

.callout--info {
  border-color: oklch(75% 0.12 220 / .45);
  background: oklch(75% 0.12 220 / .08);
}

code,
pre {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;
}

:not(pre) > code {
  padding: .08rem .35rem;
  border: 1px solid var(--line);
  border-radius: .35rem;
  background: var(--code);
  color: var(--primary);
  font-size: .9em;
}

pre {
  overflow: auto;
  padding: var(--space-4);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--code);
  color: var(--text);
  line-height: 1.55;
}

.code-block {
  max-width: 100%;
}

.code-block pre {
  margin: 0;
}

.mermaid-card {
  overflow: auto;
  padding: var(--space-4);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--code);
}

.mermaid {
  min-width: 58rem;
}

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

.arch-overview {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(14rem, 1fr));
  gap: var(--space-4);
  margin: var(--space-6) 0 var(--space-5);
}

.arch-card,
.arch-layer,
.flow-step,
.state-key {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: oklch(22% 0.018 250 / .72);
}

.arch-card {
  display: grid;
  gap: var(--space-2);
  padding: var(--space-4);
}

.arch-card__label,
.arch-layer__label,
.flow-step__label {
  color: var(--dim);
  font-size: .74rem;
  font-weight: 750;
  letter-spacing: .06em;
  text-transform: uppercase;
}

.arch-card strong {
  color: var(--text);
  font-size: 1.05rem;
  line-height: 1.25;
}

.arch-card span {
  color: var(--muted);
  font-size: .9rem;
  line-height: 1.45;
}

.arch-reading {
  display: grid;
  grid-template-columns: minmax(0, .8fr) minmax(0, 1.2fr);
  gap: var(--space-5);
  align-items: start;
}

.arch-reading__steps {
  display: grid;
  gap: var(--space-3);
  margin: 0;
  padding: 0;
  list-style: none;
}

.arch-reading__steps li {
  display: grid;
  grid-template-columns: 2rem minmax(0, 1fr);
  gap: var(--space-3);
  align-items: start;
}

.arch-reading__steps b {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 2rem;
  height: 2rem;
  border: 1px solid var(--line-strong);
  border-radius: 999px;
  color: var(--primary);
  font-size: .85rem;
}

.arch-reading__steps span {
  color: var(--text);
}

.arch-map {
  display: grid;
  gap: var(--space-3);
}

.arch-layer {
  display: grid;
  grid-template-columns: 10rem minmax(0, 1fr) minmax(12rem, .55fr);
  gap: var(--space-4);
  align-items: center;
  padding: var(--space-4);
}

.arch-layer strong {
  color: var(--primary);
}

.arch-layer p {
  margin: .25rem 0 0;
  color: var(--muted);
}

.arch-layer__meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}

.arch-mini {
  display: inline-flex;
  align-items: center;
  min-height: 1.65rem;
  padding: .1rem .5rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--muted);
  background: var(--panel);
  font-size: .78rem;
  font-weight: 650;
}

.flow-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(17rem, 1fr));
  gap: var(--space-4);
}

.flow-step {
  display: grid;
  gap: var(--space-3);
  padding: var(--space-4);
}

.flow-step h3 {
  margin: 0;
}

.flow-step ol {
  display: grid;
  gap: var(--space-2);
  margin: 0;
  padding-left: 1.2rem;
  color: var(--text);
}

.flow-step li::marker {
  color: var(--primary);
  font-weight: 800;
}

.state-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(16rem, 1fr));
  gap: var(--space-4);
}

.state-key {
  padding: var(--space-4);
}

.state-key h3 {
  margin-top: 0;
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: var(--space-4) 0;
  font-size: .92rem;
}

th,
td {
  padding: .7rem .8rem;
  border-bottom: 1px solid var(--line);
  text-align: left;
  vertical-align: top;
}

th {
  color: var(--muted);
  background: var(--panel);
  font-size: .78rem;
  letter-spacing: .04em;
  text-transform: uppercase;
}

.diagram {
  display: grid;
  gap: var(--space-3);
  padding: var(--space-4);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
}

.route-line {
  display: grid;
  grid-template-columns: repeat(4, minmax(7rem, 1fr));
  gap: var(--space-3);
}

.node {
  position: relative;
  min-height: 4.5rem;
  padding: var(--space-3);
  border: 1px solid var(--line-strong);
  border-radius: .55rem;
  background: var(--panel-2);
}

.node::after {
  content: "";
  position: absolute;
  top: 50%;
  right: calc(var(--space-3) * -1);
  width: var(--space-3);
  height: 1px;
  background: var(--line-strong);
}

.node:last-child::after {
  display: none;
}

.node strong {
  display: block;
  color: var(--primary);
}

.node span {
  display: block;
  margin-top: .25rem;
  color: var(--muted);
  font-size: .82rem;
}

.pager {
  justify-content: space-between;
  margin-top: var(--space-7);
  padding-top: var(--space-5);
  border-top: 1px solid var(--line);
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 2.5rem;
  padding: .55rem .85rem;
  border: 1px solid var(--line);
  border-radius: .5rem;
  background: var(--panel);
  color: var(--text);
  font-weight: 700;
}

.button:hover {
  border-color: var(--primary);
  color: var(--primary);
  text-decoration: none;
}

.button--primary {
  border-color: var(--primary);
  background: var(--primary);
  color: var(--primary-ink);
}

.button--primary:hover {
  color: var(--primary-ink);
  filter: brightness(1.05);
}

.quiz-question {
  padding: var(--space-4);
  margin-bottom: var(--space-4);
}

.quiz-question h2 {
  margin-top: 0;
  font-size: 1.05rem;
}

.answer {
  display: block;
  margin-top: var(--space-2);
  padding: var(--space-3);
  border: 1px solid var(--line);
  border-radius: .5rem;
  background: var(--panel);
}

.answer:hover {
  border-color: var(--line-strong);
  background: var(--panel-2);
}

.answer input {
  margin-right: var(--space-2);
  accent-color: var(--primary);
}

.text-answer {
  width: 100%;
  margin-top: var(--space-2);
  padding: .65rem;
  border: 1px solid var(--line);
  border-radius: .5rem;
  background: var(--code);
  color: var(--text);
}

.text-answer:focus-visible {
  border-color: var(--info);
}

.sources {
  margin-top: var(--space-7);
  color: var(--muted);
  font-size: .85rem;
}

@media (max-width: 58rem) {
  .app-shell {
    grid-template-columns: 1fr;
  }

  .sidebar {
    position: static;
    height: auto;
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }

  .topbar {
    position: static;
    padding: var(--space-3) var(--space-4);
  }

  .page,
  .page--lesson {
    display: block;
    padding: var(--space-5) var(--space-4);
  }

  .aside {
    position: static;
    margin-top: var(--space-5);
  }

  .lesson-item {
    grid-template-columns: 1fr;
    gap: var(--space-2);
  }

  table {
    display: block;
    overflow-x: auto;
    white-space: nowrap;
  }

  .route-line {
    grid-template-columns: 1fr;
  }

  .arch-reading,
  .arch-layer {
    grid-template-columns: 1fr;
  }

  .node::after {
    display: none;
  }
}

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