:root {
  --bg: #ffffff;
  --bg-soft: #f6f8fa;
  --ink: #1f2328;
  --muted: #59636e;
  --line: #d1d9e0;
  --accent: #0d9488;
  --accent-ink: #0f766e;
  --link: #0969da;
  --code-bg: #f6f8fa;
  --kw: #cf222e;
  --dt: #8250df;
  --num: #0550ae;
  --str: #0a3069;
  --com: #6e7781;
  --fn: #6639ba;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1419;
    --bg-soft: #161b22;
    --ink: #e6edf3;
    --muted: #9198a1;
    --line: #30363d;
    --accent: #2dd4bf;
    --accent-ink: #5eead4;
    --link: #58a6ff;
    --code-bg: #161b22;
    --kw: #ff7b72;
    --dt: #d2a8ff;
    --num: #79c0ff;
    --str: #a5d6ff;
    --com: #8b949e;
    --fn: #d2a8ff;
  }
}

* { box-sizing: border-box; }

html { scroll-padding-top: 72px; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 17px/1.65 -apple-system, "Segoe UI", Helvetica, Arial, sans-serif;
  -webkit-text-size-adjust: 100%;
}

a { color: var(--link); text-decoration: none; }
a:hover { text-decoration: underline; }

/* top bar */
.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 12px 24px;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
}
.brand { font-weight: 700; color: var(--ink); letter-spacing: -0.01em; }
.brand span { color: var(--accent); }
.topbar nav { display: flex; gap: 20px; font-size: 15px; }
.topbar nav a { color: var(--muted); }
.topbar nav a:hover { color: var(--ink); text-decoration: none; }

/* hero */
.hero {
  max-width: 1180px;
  margin: 0 auto;
  padding: 56px 24px 40px;
}
.hero h1 {
  margin: 0 0 16px;
  font-size: clamp(30px, 5vw, 46px);
  line-height: 1.15;
  letter-spacing: -0.02em;
  border: 0;
}
.hero p { max-width: 720px; color: var(--muted); font-size: 19px; margin: 0 0 24px; }
.actions { display: flex; flex-wrap: wrap; gap: 12px; }
.button {
  display: inline-block;
  padding: 9px 18px;
  border-radius: 8px;
  background: var(--accent-ink);
  color: #fff;
  font-weight: 600;
  font-size: 15px;
}
.button:hover { text-decoration: none; filter: brightness(1.08); }
.button.ghost { background: transparent; color: var(--ink); border: 1px solid var(--line); }

/* two-column layout */
.layout {
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 24px 64px;
  display: grid;
  grid-template-columns: 260px minmax(0, 1fr);
  gap: 48px;
}
.sidebar { position: relative; }
.sidebar details {
  position: sticky;
  top: 72px;
  max-height: calc(100vh - 90px);
  overflow: auto;
  font-size: 14px;
}
.sidebar summary {
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted);
  cursor: pointer;
  margin-bottom: 8px;
  list-style: none;
}
.sidebar summary::-webkit-details-marker { display: none; }
#toc ul { list-style: none; margin: 0; padding: 0; }
#toc ul ul { padding-left: 14px; }
#toc a {
  display: block;
  padding: 3px 10px;
  border-left: 2px solid transparent;
  color: var(--muted);
  line-height: 1.4;
}
#toc > ul > li > a { color: var(--ink); font-weight: 600; margin-top: 10px; }
#toc a:hover { color: var(--ink); text-decoration: none; }
#toc a.active { color: var(--accent-ink); border-left-color: var(--accent); }

/* content */
.content { max-width: 800px; min-width: 0; }
.content h1, .content h2, .content h3 { line-height: 1.25; letter-spacing: -0.01em; }
.content h1 {
  font-size: 32px;
  margin: 56px 0 16px;
  padding-top: 24px;
  border-top: 1px solid var(--line);
}
.content > h1:first-child { margin-top: 0; padding-top: 0; border-top: 0; }
.content h2 { font-size: 24px; margin: 44px 0 12px; }
.content h3 { font-size: 19px; margin: 32px 0 8px; }
.content p, .content li { overflow-wrap: anywhere; }
.content li + li { margin-top: 4px; }

code {
  font-family: ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  font-size: 0.86em;
  background: var(--code-bg);
  border: 1px solid var(--line);
  border-radius: 5px;
  padding: 0.1em 0.35em;
}
pre {
  background: var(--code-bg);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 16px;
  overflow-x: auto;
  font-size: 14px;
  line-height: 1.5;
}
pre code { background: none; border: 0; padding: 0; font-size: inherit; }
div.sourceCode { margin: 16px 0; }
.sourceCode .kw, .sourceCode .cf { color: var(--kw); }
.sourceCode .dt { color: var(--dt); }
.sourceCode .dv, .sourceCode .fl, .sourceCode .bn { color: var(--num); }
.sourceCode .st, .sourceCode .ch { color: var(--str); }
.sourceCode .co { color: var(--com); font-style: italic; }
.sourceCode .fu { color: var(--fn); }
.sourceCode .pp { color: var(--kw); }

figure {
  margin: 28px 0;
  padding: 0;
}
figure img {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: #fff;
}
figcaption {
  margin-top: 10px;
  font-size: 14px;
  color: var(--muted);
  text-align: center;
}

blockquote {
  margin: 16px 0;
  padding: 4px 16px;
  border-left: 3px solid var(--accent);
  color: var(--muted);
}

footer {
  margin-top: 64px;
  padding-top: 16px;
  border-top: 1px solid var(--line);
  font-size: 14px;
  color: var(--muted);
}

/* narrow screens */
@media (max-width: 959px) {
  .layout { grid-template-columns: minmax(0, 1fr); gap: 8px; padding: 0 16px 48px; }
  .hero { padding: 36px 16px 24px; }
  .topbar { padding: 12px 16px; }
  .sidebar details {
    position: static;
    max-height: none;
    border: 1px solid var(--line);
    border-radius: 8px;
    padding: 10px 14px;
    background: var(--bg-soft);
  }
  .sidebar summary { margin: 0; }
  .sidebar details[open] summary { margin-bottom: 8px; }
  .hero p { font-size: 17px; }
  /* keep figures legible: scroll sideways instead of shrinking */
  figure { overflow-x: auto; }
  figure img { min-width: 640px; }
}
@media (max-width: 520px) {
  .topbar nav a:first-child { display: none; }
}