/* Surface website — blue-themed minimal stylesheet. */

:root {
  --primary: #1e3a8a;
  --primary-hover: #1e40af;
  --accent: #2563eb;
  --accent-hover: #3b82f6;

  --bg: #f8fafc;
  --surface: #ffffff;
  --border: #dbeafe;
  --border-strong: #bfdbfe;

  --text: #0f172a;
  --muted: #475569;

  --code-bg: #eff6ff;
  --code-border: #c7d2fe;

  --badge-bg: #fef3c7;
  --badge-fg: #92400e;
  --badge-border: #fcd34d;

  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono: "JetBrains Mono", "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;

  --radius: 6px;
  --shadow: 0 1px 2px rgba(15, 23, 42, 0.04), 0 1px 4px rgba(15, 23, 42, 0.06);
  --container-w: 760px;
  --sidebar-w: 240px;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

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

/* ── Header ── */
.site-header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 14px 24px;
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}
.site-header .brand {
  font-weight: 700;
  font-size: 1.15rem;
  color: var(--primary);
  letter-spacing: -0.01em;
}
.site-header .brand a { color: inherit; }
.site-header .brand a:hover { text-decoration: none; color: var(--primary-hover); }

.experimental-badge {
  display: inline-block;
  padding: 3px 10px;
  background: var(--badge-bg);
  color: var(--badge-fg);
  border: 1px solid var(--badge-border);
  border-radius: 999px;
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.01em;
  white-space: nowrap;
}

.site-header .top-nav {
  display: flex;
  gap: 18px;
  font-size: 0.92rem;
}
.site-header .top-nav a { color: var(--muted); }
.site-header .top-nav a:hover { color: var(--accent); }

/* ── Page wrapper with optional sidebar ── */
.page {
  max-width: 1100px;
  margin: 0 auto;
  padding: 32px 24px 64px;
  display: grid;
  grid-template-columns: var(--sidebar-w) 1fr;
  gap: 40px;
}
.page-full {
  max-width: 1100px;
  margin: 0 auto;
  padding: 32px 24px 64px;
}

.landing-main {
  max-width: 1100px;
  margin: 0 auto;
  padding: 24px 24px 48px;
}

aside.sidebar {
  position: sticky;
  top: 80px;
  align-self: start;
  font-size: 0.94rem;
}
aside.sidebar h4 {
  margin: 0 0 8px;
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
  font-weight: 700;
}
aside.sidebar ul {
  list-style: none;
  padding: 0;
  margin: 0 0 24px;
}
aside.sidebar li { margin: 0; }
aside.sidebar a {
  display: block;
  padding: 6px 10px;
  border-radius: var(--radius);
  color: var(--text);
  border-left: 2px solid transparent;
}
aside.sidebar a:hover {
  background: var(--code-bg);
  color: var(--accent);
  text-decoration: none;
}
aside.sidebar a.active {
  background: var(--code-bg);
  color: var(--primary);
  border-left-color: var(--accent);
  font-weight: 600;
}

main { min-width: 0; }

article {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 36px 44px;
  max-width: var(--container-w);
}

article h1, article h2, article h3, article h4 {
  color: var(--primary);
  letter-spacing: -0.01em;
  line-height: 1.25;
}
article h1 {
  font-size: 2.2rem;
  margin: 0 0 8px;
}
article h1 + .post-meta {
  color: var(--muted);
  font-size: 0.9rem;
  margin: 0 0 28px;
}
article h2 {
  font-size: 1.55rem;
  margin: 36px 0 12px;
  padding-top: 8px;
  border-top: 1px solid var(--border);
}
article h3 { font-size: 1.2rem; margin: 28px 0 10px; }
article h4 { font-size: 1.0rem; margin: 22px 0 8px; }

article p, article li { color: var(--text); }
article ul, article ol { padding-left: 24px; }
article li { margin: 4px 0; }

article blockquote {
  border-left: 3px solid var(--accent);
  background: var(--code-bg);
  padding: 12px 18px;
  margin: 16px 0;
  color: var(--muted);
  border-radius: 0 var(--radius) var(--radius) 0;
}
article blockquote p { margin: 6px 0; }

article hr {
  border: none;
  border-top: 1px solid var(--border);
  margin: 28px 0;
}

/* ── Code ── */
code, pre, kbd {
  font-family: var(--mono);
  font-size: 0.92em;
}
article :not(pre) > code {
  background: var(--code-bg);
  border: 1px solid var(--border);
  padding: 1px 6px;
  border-radius: 4px;
  font-size: 0.88em;
}
article pre {
  background: var(--code-bg);
  border: 1px solid var(--code-border);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius);
  padding: 14px 18px;
  overflow-x: auto;
  line-height: 1.5;
  font-size: 0.88rem;
}
article pre code { background: transparent; border: none; padding: 0; }

/* ── Tables ── */
article table {
  width: 100%;
  border-collapse: collapse;
  margin: 18px 0;
  font-size: 0.94rem;
}
article th, article td {
  border: 1px solid var(--border);
  padding: 8px 12px;
  text-align: left;
  vertical-align: top;
}
article th {
  background: var(--code-bg);
  color: var(--primary);
  font-weight: 600;
}
article tbody tr:nth-child(even) { background: rgba(239, 246, 255, 0.4); }

/* ── ToC ── */
details.toc {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 10px 16px;
  margin: 0 0 28px;
  font-size: 0.94rem;
}
details.toc summary {
  cursor: pointer;
  font-weight: 600;
  color: var(--primary);
}
details.toc ul { padding-left: 22px; margin: 8px 0 4px; }
details.toc li { margin: 2px 0; }

/* ── Footer ── */
.site-footer {
  border-top: 1px solid var(--border);
  background: var(--surface);
  padding: 24px;
  margin-top: 48px;
  text-align: center;
  color: var(--muted);
  font-size: 0.88rem;
}
.site-footer a { color: var(--muted); }
.site-footer a:hover { color: var(--accent); }

/* ── Landing-specific ── */
.hero {
  text-align: center;
  padding: 48px 16px 32px;
  max-width: 760px;
  margin: 0 auto;
}
.hero h1 {
  font-size: 3rem;
  margin: 0 0 12px;
  color: var(--primary);
  letter-spacing: -0.02em;
}
.hero .tagline {
  font-size: 1.2rem;
  color: var(--muted);
  margin: 0 0 28px;
}
.hero .cta {
  display: inline-flex;
  gap: 12px;
  flex-wrap: wrap;
  justify-content: center;
}
.btn {
  display: inline-block;
  padding: 10px 20px;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: 0.96rem;
  border: 1px solid transparent;
  transition: background 120ms ease, border-color 120ms ease;
}
.btn-primary {
  background: var(--primary);
  color: white !important;
}
.btn-primary:hover {
  background: var(--primary-hover);
  text-decoration: none;
}
.btn-secondary {
  background: var(--surface);
  color: var(--primary) !important;
  border-color: var(--border-strong);
}
.btn-secondary:hover {
  background: var(--code-bg);
  text-decoration: none;
}

.featured-code {
  max-width: 760px;
  margin: 0 auto 48px;
}
.featured-code h3 {
  text-align: center;
  color: var(--muted);
  font-weight: 500;
  font-size: 0.92rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin: 0 0 12px;
}
.featured-code pre {
  background: var(--code-bg);
  border: 1px solid var(--code-border);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius);
  padding: 18px 22px;
  font-family: var(--mono);
  font-size: 0.9rem;
  overflow-x: auto;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
  max-width: 1000px;
  margin: 0 auto 48px;
}
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px 22px;
  box-shadow: var(--shadow);
}
.card h3 {
  margin: 0 0 8px;
  font-size: 1.05rem;
  color: var(--primary);
}
.card p {
  margin: 0 0 12px;
  color: var(--muted);
  font-size: 0.94rem;
  line-height: 1.55;
}
.card a { font-size: 0.9rem; font-weight: 600; }

.what-table {
  max-width: 900px;
  margin: 0 auto 48px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 8px 12px;
  box-shadow: var(--shadow);
}
.what-table table { margin: 0; }

.section-heading {
  text-align: center;
  color: var(--primary);
  font-size: 1.6rem;
  margin: 8px 0 24px;
}

/* ── Responsive ── */
@media (max-width: 900px) {
  .page {
    grid-template-columns: 1fr;
    gap: 24px;
  }
  aside.sidebar {
    position: static;
    border-bottom: 1px solid var(--border);
    padding-bottom: 16px;
  }
  article { padding: 24px 22px; }
  .card-grid { grid-template-columns: 1fr; }
  .hero h1 { font-size: 2.2rem; }
  .site-header { flex-wrap: wrap; gap: 10px; }
  .site-header .top-nav { width: 100%; justify-content: flex-start; }
}