:root {
  color-scheme: dark;
  --bg: #070a0f;
  --panel: #0d1119;
  --panel-strong: #121826;
  --panel-soft: #161e2d;
  --text: #e6edf7;
  --muted: #9aa8bd;
  --nav-chapter: #b89b63;
  --line: #263247;
  --accent: #7dd3fc;
  --accent-strong: #38bdf8;
  --accent-soft: rgba(56, 189, 248, 0.14);
  --green: #86efac;
  --yellow: #fde68a;
  --red: #fca5a5;
  --code: #05070b;
  --shadow: 0 24px 80px rgba(0, 0, 0, 0.35);
  --page-gutter: clamp(1rem, 3vw, 2.5rem);
  --sidebar-width: clamp(17rem, 24vw, 20rem);
  --sidebar-rail-width: calc(var(--sidebar-width) + var(--page-gutter));
  --header-height: 4.6rem;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  background:
    radial-gradient(circle at top left, rgba(56, 189, 248, 0.12), transparent 30rem),
    radial-gradient(circle at top right, rgba(134, 239, 172, 0.08), transparent 26rem),
    var(--bg);
  color: var(--text);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.65;
}

a {
  color: inherit;
}

.app-shell {
  min-height: 100vh;
  padding-top: var(--header-height);
  transition: padding-top 220ms ease;
}

.header-hidden .app-shell {
  padding-top: 0;
}

.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 1rem var(--page-gutter);
  border-bottom: 1px solid rgba(148, 163, 184, 0.16);
  background: rgba(7, 10, 15, 0.88);
  backdrop-filter: blur(16px);
  transform: translateY(0);
  transition: transform 220ms ease, opacity 220ms ease;
}

.header-hidden .site-header {
  opacity: 0;
  pointer-events: none;
  transform: translateY(-110%);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.8rem;
  text-decoration: none;
}

.brand-mark {
  display: block;
  width: 2.64rem;
  height: 2.64rem;
  animation: rust-logo-spin 12s linear infinite;
  object-fit: contain;
  transform-origin: center;
}

@keyframes rust-logo-spin {
  from {
    transform: rotate(0deg);
  }

  to {
    transform: rotate(360deg);
  }
}

.brand strong,
.brand small {
  display: block;
}

.brand small {
  color: var(--muted);
  font-size: 0.78rem;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.language-toggle,
.repo-link,
.nav-button {
  border: 1px solid rgba(125, 211, 252, 0.34);
  border-radius: 999px;
  background: rgba(13, 17, 25, 0.82);
  color: var(--text);
  cursor: pointer;
  font: inherit;
  padding: 0.6rem 0.95rem;
  text-decoration: none;
  transition: border-color 160ms ease, background 160ms ease, transform 160ms ease;
}

.star-cta {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  font-weight: 800;
}

.star-cta-icon {
  color: var(--yellow);
  line-height: 1;
  text-shadow: 1px 1px 0 rgba(253, 230, 138, 0.26);
}

.star-cta-count {
  border-left: 1px solid rgba(148, 163, 184, 0.22);
  color: var(--yellow);
  font-variant-numeric: tabular-nums;
  margin-left: 0.1rem;
  padding-left: 0.45rem;
}

.star-cta-acknowledged {
  border-color: rgba(134, 239, 172, 0.45);
  background: rgba(134, 239, 172, 0.1);
}

.language-toggle:hover,
.repo-link:hover,
.nav-button:hover {
  border-color: var(--accent);
  background: var(--accent-soft);
  transform: translateY(-1px);
}

.layout {
  display: grid;
  grid-template-columns: var(--sidebar-rail-width) minmax(0, 1fr);
  gap: clamp(1rem, 3vw, 2rem);
  padding: var(--page-gutter);
}

.sidebar {
  position: fixed;
  top: var(--header-height);
  bottom: 0;
  left: 0;
  z-index: 10;
  width: var(--sidebar-rail-width);
  max-height: none;
  overflow: auto;
  scrollbar-gutter: stable;
  scrollbar-width: thin;
  scrollbar-color: rgba(148, 163, 184, 0.35) transparent;
  border: 1px solid rgba(148, 163, 184, 0.16);
  border-top: 0;
  border-bottom: 0;
  border-left: 0;
  border-radius: 0;
  background: rgba(13, 17, 25, 0.76);
  box-shadow: var(--shadow);
  padding: var(--page-gutter) 1rem var(--page-gutter) var(--page-gutter);
  transition: top 220ms ease;
}

.sidebar::-webkit-scrollbar {
  width: 8px;
}

.sidebar::-webkit-scrollbar-track {
  background: transparent;
}

.sidebar::-webkit-scrollbar-thumb {
  background: rgba(148, 163, 184, 0.35);
  border-radius: 999px;
}

.sidebar::-webkit-scrollbar-thumb:hover {
  background: rgba(148, 163, 184, 0.55);
}

.header-hidden .sidebar {
  top: 0;
}

.part-tabs {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.45rem;
  margin-bottom: 1rem;
}

.part-tab {
  border: 1px solid rgba(125, 211, 252, 0.22);
  border-radius: 0.8rem;
  background: rgba(18, 24, 38, 0.76);
  color: var(--muted);
  cursor: pointer;
  font: inherit;
  font-weight: 800;
  padding: 0.55rem 0.7rem;
}

.part-tab:hover,
.part-tab.active {
  border-color: rgba(125, 211, 252, 0.55);
  background: var(--accent-soft);
  color: var(--text);
}

.nav-part {
  margin-bottom: 1rem;
}

.nav-chapter-title {
  color: var(--nav-chapter);
  font-size: 0.7rem;
  font-weight: 700;
  line-height: 1.2;
  margin: 0.75rem 0 0.2rem;
}

.nav-section {
  display: block;
  width: 100%;
  border: 0;
  border-radius: 0.75rem;
  background: transparent;
  color: var(--muted);
  cursor: pointer;
  font: inherit;
  margin: 0.15rem 0;
  padding: 0.45rem 0.6rem;
  text-align: left;
}

.nav-section:hover,
.nav-section.active {
  background: var(--accent-soft);
  color: var(--text);
}

.main-content {
  grid-column: 2;
  min-width: 0;
}

.lesson {
  border: 1px solid rgba(148, 163, 184, 0.16);
  border-radius: 1.5rem;
  background: rgba(13, 17, 25, 0.78);
  box-shadow: var(--shadow);
}

.lesson h1 {
  font-size: clamp(2rem, 5vw, 4rem);
  line-height: 1.05;
  margin: 0.6rem 0 1rem;
}

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

.content-card,
.comparison-card,
.examples,
.references {
  border: 1px solid rgba(148, 163, 184, 0.15);
  border-radius: 1rem;
  background: rgba(18, 24, 38, 0.76);
}

.lesson {
  padding: clamp(1.25rem, 3vw, 2.5rem);
}

.lesson-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 32rem), 1fr));
  gap: 1rem;
}

.content-card,
.comparison-card,
.examples,
.references {
  margin-top: 1rem;
  padding: 1.1rem;
}

.content-card h2,
.comparison-card h2,
.examples h2,
.references h2 {
  margin: 0 0 0.75rem;
}

.content-card.syntax {
  border-color: rgba(125, 211, 252, 0.24);
}

.content-card.engineering {
  border-color: rgba(134, 239, 172, 0.22);
}

.comparison-card {
  border-color: rgba(253, 230, 138, 0.2);
}

.comparison-card h2 {
  color: var(--yellow);
}

.content-card ul,
.references ul {
  margin: 0;
  padding-left: 1.2rem;
}

.content-card li,
.references li {
  color: var(--muted);
  margin: 0.35rem 0;
}

.examples-grid {
  display: grid;
  gap: 1rem;
}

.explanation-card {
  border: 1px solid rgba(125, 211, 252, 0.18);
  border-radius: 0.9rem;
  background: rgba(18, 24, 38, 0.64);
  padding: 1rem;
}

.explanation-card h3 {
  color: var(--accent);
  margin: 0 0 0.7rem;
}

.explanation-card p {
  margin: 0.45rem 0;
}

.example-diagram {
  border: 1px solid rgba(148, 163, 184, 0.16);
  border-radius: 0.75rem;
  background: var(--code);
  color: var(--text);
  margin-top: 0.9rem;
}

.file-tree-card {
  grid-column: 1 / -1;
}

.file-tree-panel {
  overflow: hidden;
  border: 1px solid rgba(148, 163, 184, 0.16);
  border-radius: 0.7rem;
  background: rgba(5, 7, 11, 0.46);
  margin-top: 0.65rem;
}

.file-tree-root {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  border-bottom: 1px solid rgba(148, 163, 184, 0.14);
  background: rgba(2, 6, 23, 0.32);
  padding: 0.34rem 0.55rem;
}

.file-tree-root-icon,
.file-tree-dir .file-tree-badge,
.file-tree-file .file-tree-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.file-tree-root-icon {
  width: 0.58rem;
  height: 0.58rem;
  border: 1px solid var(--accent);
  border-radius: 0.18rem;
}

.file-tree-list {
  display: grid;
  margin: 0;
  padding: 0.18rem 0.45rem;
}

.file-tree-item {
  display: flex;
  align-items: center;
  border-bottom: 1px solid rgba(148, 163, 184, 0.08);
  border-radius: 0.35rem;
  outline: none;
  padding: 0.16rem 0.18rem 0.16rem calc(0.18rem + var(--tree-indent, 0rem));
}

.file-tree-item:hover,
.file-tree-item:focus-visible {
  background: rgba(125, 211, 252, 0.06);
}

.file-tree-node {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  min-width: 0;
}

.file-tree-badge {
  min-width: 2.35rem;
  border: 1px solid rgba(148, 163, 184, 0.2);
  border-radius: 0.35rem;
  color: var(--muted);
  font-size: 0.58rem;
  font-weight: 900;
  letter-spacing: 0.06em;
  padding: 0.08rem 0.3rem;
  text-transform: uppercase;
}

.file-tree-dir .file-tree-badge {
  border-color: rgba(253, 230, 138, 0.34);
  color: var(--yellow);
}

.file-tree-dir code {
  color: var(--yellow);
}

.file-tree-file .file-tree-badge {
  border-color: rgba(134, 239, 172, 0.22);
  color: var(--green);
}

.file-tree-file code {
  color: var(--green);
}

.file-tree-tooltip {
  position: fixed;
  z-index: 1200;
  max-width: min(30rem, calc(100vw - 1rem));
  border: 1px solid rgba(125, 211, 252, 0.28);
  border-radius: 0.7rem;
  background: var(--panel-strong);
  box-shadow: 0 18px 48px rgba(0, 0, 0, 0.5);
  padding: 0.65rem 0.75rem;
  color: var(--text);
  font-size: 0.84rem;
  line-height: 1.55;
  pointer-events: none;
}

.file-tree-tooltip[hidden] {
  display: none;
}

.file-tree-tooltip code {
  border: 1px solid rgba(148, 163, 184, 0.18);
  border-radius: 0.35rem;
  background: rgba(255, 255, 255, 0.06);
  color: var(--green);
  padding: 0.08rem 0.28rem;
}

.table-card {
  grid-column: 1 / -1;
}

.table-scroll {
  overflow-x: auto;
  margin-top: 0.8rem;
}

.table-search {
  display: grid;
  gap: 0.4rem;
  color: var(--muted);
  font-size: 0.9rem;
  margin: 0.4rem 0 0.8rem;
}

.table-search-input {
  width: min(100%, 32rem);
  border: 1px solid rgba(125, 211, 252, 0.34);
  border-radius: 999px;
  background: rgba(5, 7, 11, 0.72);
  color: var(--text);
  font: inherit;
  padding: 0.65rem 0.9rem;
}

.table-search-input:focus {
  border-color: var(--accent);
  outline: 2px solid rgba(125, 211, 252, 0.2);
}

.compare-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}

.searchable-table {
  min-width: 70rem;
}

.method-search-results,
.method-table-groups {
  display: grid;
  gap: 1rem;
}

.method-search-results[hidden],
.method-table-groups[hidden] {
  display: none;
}

.method-search-results h4,
.method-table-group h4 {
  color: var(--accent);
  margin: 0.2rem 0 0.4rem;
}

.method-table-group {
  border-top: 1px solid rgba(148, 163, 184, 0.16);
  padding-top: 0.9rem;
}

.method-result-table,
.method-group-table {
  min-width: 52rem;
}

.compare-table th,
.compare-table td {
  border: 1px solid rgba(148, 163, 184, 0.18);
  padding: 0.5rem 0.7rem;
  text-align: left;
  vertical-align: top;
}

.source-summary-row {
  cursor: pointer;
}

.source-summary-row:hover {
  background: rgba(125, 211, 252, 0.08);
}

.source-toggle {
  border: 0;
  background: transparent;
  color: var(--accent);
  cursor: pointer;
  font: inherit;
  font-weight: 800;
  padding: 0;
  text-align: left;
}

.source-toggle::before {
  content: "▸";
  display: inline-block;
  margin-right: 0.4rem;
  transition: transform 140ms ease;
}

.source-summary-row[aria-expanded="true"] .source-toggle::before {
  transform: rotate(90deg);
}

.source-code-row pre {
  margin: 0;
  max-height: min(62vh, 42rem);
}

.compare-table thead th {
  background: rgba(56, 189, 248, 0.1);
  color: var(--text);
  font-weight: 700;
}

.compare-table tbody tr:nth-child(even) {
  background: rgba(148, 163, 184, 0.05);
}

.compare-table tr[hidden] {
  display: none;
}

.compare-table code {
  white-space: nowrap;
}

.compare-table .source-code-row code {
  display: block;
  white-space: pre;
}

.method-signature-code {
  color: var(--text);
}

.code-card {
  overflow: hidden;
  border: 1px solid rgba(148, 163, 184, 0.16);
  border-radius: 0.9rem;
  background: var(--code);
}

.code-card.has-mistakes {
  border-color: rgba(252, 165, 165, 0.24);
}

.code-header {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  border-bottom: 1px solid rgba(148, 163, 184, 0.14);
  background: rgba(255, 255, 255, 0.03);
  color: var(--muted);
  font-size: 0.84rem;
  padding: 0.65rem 0.85rem;
}

pre {
  margin: 0;
  overflow: auto;
  padding: 1rem;
}

.mistake-list {
  display: grid;
  gap: 0.9rem;
  border-top: 1px solid rgba(252, 165, 165, 0.2);
  background: rgba(127, 29, 29, 0.1);
  padding: 1rem;
}

.mistake-card {
  overflow: hidden;
  border: 1px solid rgba(252, 165, 165, 0.35);
  border-left: 0.35rem solid var(--red);
  border-radius: 0.8rem;
  background: rgba(69, 10, 10, 0.34);
}

.mistake-title {
  border-bottom: 1px solid rgba(252, 165, 165, 0.22);
  color: var(--red);
  font-weight: 800;
  padding: 0.65rem 0.85rem;
}

.mistake-code {
  background: rgba(0, 0, 0, 0.34);
}

.mistake-detail {
  padding: 0 0.85rem 0.85rem;
}

.mistake-detail strong {
  display: block;
  color: var(--text);
  margin: 0.7rem 0 0.25rem;
}

.mistake-detail p {
  color: #fecaca;
  margin: 0.25rem 0;
}

.mistake-error p:first-of-type {
  color: var(--red);
  font-weight: 800;
}

code {
  font-family: "Cascadia Code", "SFMono-Regular", Consolas, "Liberation Mono", "Microsoft YaHei", "PingFang SC", "Hiragino Sans GB", "Noto Sans CJK SC", "Noto Sans SC", monospace;
  font-size: 0.9rem;
}

.tok-comment {
  color: #5fa85f;
  font-style: italic;
}

.tok-keyword {
  color: #ff7b72;
}

.tok-type {
  color: #4ec9b0;
}

.tok-fn {
  color: #dcdcaa;
}

.method-ref {
  border-radius: 0.25rem;
  cursor: help;
  text-shadow: 1.5px 1.5px 0 rgba(56, 189, 248, 0.45);
  transition: text-shadow 140ms ease, background 140ms ease, box-shadow 140ms ease;
}

.ident-highlight {
  border-radius: 0.2rem;
  background: rgba(125, 211, 252, 0.2);
  box-shadow: 0 0 0 1px rgba(125, 211, 252, 0.25);
}

.method-ref:hover,
.method-ref:focus-visible {
  background: rgba(56, 189, 248, 0.14);
  box-shadow: 0 0 0 0.12rem rgba(56, 189, 248, 0.22);
  text-shadow: 1px 1px 0 rgba(56, 189, 248, 0.3);
  outline: none;
}

.method-tooltip {
  position: fixed;
  z-index: 1200;
  max-width: min(28rem, calc(100vw - 1rem));
  border: 1px solid rgba(125, 211, 252, 0.28);
  border-radius: 0.7rem;
  background: var(--panel-strong);
  box-shadow: 0 18px 48px rgba(0, 0, 0, 0.5);
  padding: 0.7rem 0.8rem;
  color: var(--text);
  font-size: 0.84rem;
  line-height: 1.55;
  pointer-events: none;
}

.method-tooltip[hidden] {
  display: none;
}

.method-tooltip-item {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
}

.method-tooltip-item + .method-tooltip-item {
  margin-top: 0.6rem;
  padding-top: 0.6rem;
  border-top: 1px solid rgba(148, 163, 184, 0.18);
}

.method-tooltip-sig {
  display: block;
  white-space: pre-wrap;
  word-break: break-word;
}

.method-tooltip-group {
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--accent);
}

.method-tooltip-note {
  color: var(--muted);
}

.tok-macro {
  color: #c586c0;
}

.tok-string {
  color: #ce9178;
}

.tok-number {
  color: #b5cea8;
}

.tok-lifetime {
  color: #ffa657;
}

.tok-literal {
  color: #569cd6;
}

.tok-attribute {
  color: #9aa8bd;
}

p code,
li code {
  border: 1px solid rgba(148, 163, 184, 0.18);
  border-radius: 0.35rem;
  background: rgba(255, 255, 255, 0.06);
  color: var(--green);
  padding: 0.08rem 0.28rem;
}

.lesson-footer {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 1.5rem;
}

.nav-button[disabled] {
  cursor: not-allowed;
  opacity: 0.4;
  transform: none;
}

.noscript {
  background: var(--red);
  color: #1f0a0a;
  padding: 1rem;
}

@media (max-width: 980px) {
  .layout {
    grid-template-columns: 1fr;
  }

  .sidebar {
    position: static;
    width: auto;
    max-height: none;
  }

  .main-content {
    grid-column: auto;
  }

  .lesson-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 640px) {
  .site-header {
    align-items: flex-start;
    flex-direction: column;
  }

  .header-actions,
  .lesson-footer {
    width: 100%;
  }

  .language-toggle,
  .repo-link,
  .nav-button {
    justify-content: center;
    text-align: center;
    flex: 1;
  }

  .file-tree-item {
    display: flex;
  }
}