*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

  :root[data-theme="dark"] {
    --bg: #0d1117;
    --surface: #161b22;
    --border: #30363d;
    --text: #c9d1d9;
    --muted: #8b949e;
    --accent: #58a6ff;
    --code-bg: #161b22;
  }

  :root[data-theme="light"] {
    --bg: #ffffff;
    --surface: #f6f8fa;
    --border: #d0d7de;
    --text: #24292f;
    --muted: #57606a;
    --accent: #0969da;
    --code-bg: #f6f8fa;
  }

  html, body {
    background: var(--bg);
    color: var(--text);
    font-family: 'Newsreader', Georgia, serif;
    font-size: 18px;
    line-height: 1.75;
    min-height: 100vh;
    scroll-behavior: smooth;
  }

  #topbar {
    position: fixed;
    top: 0; left: 0; right: 0;
    height: 44px;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    display: flex;
    align-items: center;
    padding: 0 24px;
    gap: 12px;
    z-index: 100;
  }

  #topbar .filepath {
    font-family: 'JetBrains Mono', monospace;
    font-size: 11px;
    color: var(--muted);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    flex: 1;
  }

  #topbar button {
    background: none;
    border: 1px solid var(--border);
    color: var(--muted);
    width: 28px;
    height: 28px;
    padding: 0;
    border-radius: 4px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    transition: color 0.15s, border-color 0.15s;
  }

  #topbar button:hover {
    color: var(--accent);
    border-color: var(--accent);
  }

  #layout {
    display: flex;
    max-width: 1100px;
    margin: 0 auto;
    padding: 80px 24px 80px;
    gap: 40px;
  }

  #toc-panel {
    display: none;
    width: 200px;
    flex-shrink: 0;
    position: sticky;
    top: 60px;
    max-height: calc(100vh - 80px);
    overflow-y: auto;
    align-self: flex-start;
  }

  #toc-panel.visible { display: block; }

  #toc-title {
    font-family: 'JetBrains Mono', monospace;
    font-size: 10px;
    color: var(--muted);
    text-transform: uppercase;
    letter-spacing: 0.08em;
    margin-bottom: 10px;
  }

  #toc-list { list-style: none; padding: 0; }

  #toc-list li a {
    display: block;
    font-family: 'JetBrains Mono', monospace;
    font-size: 11px;
    color: var(--muted);
    text-decoration: none;
    line-height: 1.4;
    border-left: 2px solid transparent;
    padding: 3px 0 3px 8px;
    transition: color 0.15s, border-color 0.15s;
  }

  #toc-list li a:hover,
  #toc-list li a.active {
    color: var(--accent);
    border-left-color: var(--accent);
  }

  #toc-list li.toc-h3 a { padding-left: 20px; }
  #toc-list li.toc-h4 a { padding-left: 32px; }

  #main-col { flex: 1; min-width: 0; }

  #loading, #error {
    padding-top: 120px;
    text-align: center;
    font-family: 'JetBrains Mono', monospace;
    font-size: 13px;
    color: var(--muted);
  }

  #error { color: #f85149; }

  .md { animation: fadeIn 0.4s ease-out; }

  @keyframes fadeIn {
    from { opacity: 0; transform: translateY(4px); }
    to { opacity: 1; transform: translateY(0); }
  }

  .md h1, .md h2, .md h3, .md h4, .md h5, .md h6 {
    font-family: 'Newsreader', Georgia, serif;
    font-weight: 500;
    line-height: 1.3;
    margin: 2em 0 0.6em;
    color: var(--text);
    scroll-margin-top: 60px;
    cursor: pointer;
  }

  .md h1:hover::after, .md h2:hover::after, .md h3:hover::after,
  .md h4:hover::after, .md h5:hover::after, .md h6:hover::after {
    content: " #";
    color: var(--accent);
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.8em;
  }

  .md h1 { font-size: 2rem; margin-top: 0; border-bottom: 1px solid var(--border); padding-bottom: 0.4em; }
  .md h2 { font-size: 1.45rem; border-bottom: 1px solid var(--border); padding-bottom: 0.3em; }
  .md h3 { font-size: 1.2rem; }

  .md p { margin: 1em 0; }

  .md a { color: var(--accent); text-decoration: none; }
  .md a:hover { text-decoration: underline; }

  .md code {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85em;
    background: var(--code-bg);
    padding: 2px 6px;
    border-radius: 6px;
    color: var(--text);
  }

  .md pre {
    background: var(--code-bg);
    border: 1px solid var(--border);
    border-radius: 6px;
    padding: 16px 20px;
    overflow-x: auto;
    margin: 1.4em 0;
    position: relative;
  }

  .md pre code {
    background: none;
    border: none;
    padding: 0;
    font-size: 0.84em;
    color: var(--text);
    border-radius: 0;
  }

  .pre-copy-btn {
    position: absolute;
    top: 8px; right: 8px;
    background: var(--surface);
    border: 1px solid var(--border);
    color: var(--muted);
    font-family: 'JetBrains Mono', monospace;
    font-size: 11px;
    padding: 5px 10px;
    border-radius: 4px;
    cursor: pointer;
    opacity: 0;
    transition: opacity 0.15s, color 0.15s, border-color 0.15s;
  }

  .md pre:hover .pre-copy-btn { opacity: 1; }

  .pre-copy-btn:hover {
    color: var(--accent);
    border-color: var(--accent);
  }

  .md blockquote {
    border-left: 4px solid var(--border);
    padding: 0 1em;
    margin: 1.2em 0;
    color: var(--muted);
  }

  .md ul, .md ol { padding-left: 2em; margin: 0.8em 0; }
  .md li { margin: 0.25em 0; }

  .md input[type="checkbox"] {
    margin-right: 6px;
    accent-color: var(--accent);
    vertical-align: middle;
    position: relative;
    top: -1px;
  }

  .md table {
    display: block;
    width: 100%;
    overflow-x: auto;
    border-collapse: collapse;
    margin: 1.4em 0;
    font-size: 0.9em;
  }

  .md th {
    background: var(--surface);
    border: 1px solid var(--border);
    padding: 8px 14px;
    text-align: left;
    font-weight: 500;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85em;
  }

  .md td { border: 1px solid var(--border); padding: 8px 14px; }
  .md tr:nth-child(even) td { background: var(--surface); }
  .md img { max-width: 100%; border-radius: 4px; }

  .md hr {
    border: none;
    border-top: 2px solid var(--border);
    margin: 2em 0;
  }

  @media (max-width: 900px) {
    #toc-panel { display: none !important; }
    #layout { max-width: 740px; }
  }

  @media (max-width: 600px) {
    html { font-size: 16px; }
    #layout { padding: 70px 16px 60px; }
    #topbar { padding: 0 16px; }
    .pre-copy-btn { opacity: 1; }
  }