:root {
  --bg: #f4f6fa;
  --card: #ffffff;
  --text: #0e1424;
  --muted: #5b6577;
  --line: #e5eaf2;
  --accent: #1b6ff5;
  --accent-soft: rgba(27, 111, 245, 0.1);
  --danger: #dc2626;
  --radius: 14px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b0f1a;
    --card: #141a29;
    --text: #eef2f8;
    --muted: #a3adbf;
    --line: #252d40;
    --accent: #5b9bff;
    --accent-soft: rgba(91, 155, 255, 0.14);
    --danger: #f87171;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.65 system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  padding: 0 16px;
}

a { color: var(--accent); }

.wrap { max-width: 760px; margin: 0 auto; }

.site-header {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px 20px;
  padding: 20px 0;
  border-bottom: 1px solid var(--line);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--text);
  font-weight: 800;
  font-size: 1.15rem;
  text-decoration: none;
}

.logo {
  display: inline-grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border-radius: 10px;
  background: linear-gradient(135deg, #1b6ff5, #7c4dff);
  color: #fff;
  font-size: 1.05rem;
}

.site-header nav { display: flex; flex-wrap: wrap; gap: 4px 16px; }

.site-header nav a {
  color: var(--muted);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.95rem;
}

.site-header nav a:hover,
.site-header nav a[aria-current="page"] { color: var(--accent); }

main { padding: 32px 0 8px; }

h1 { font-size: clamp(1.7rem, 5vw, 2.2rem); line-height: 1.2; margin: 0; }
h2 { font-size: 1.2rem; line-height: 1.35; margin: 0 0 10px; }
h3 { font-size: 1rem; margin: 18px 0 6px; }

.lead { color: var(--muted); margin: 8px 0 0; }
.meta { color: var(--muted); font-size: 0.9rem; margin: 10px 0 0; }

.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 20px 22px;
  margin-top: 18px;
}

.card > :last-child { margin-bottom: 0; }

.highlight { background: var(--accent-soft); border-color: transparent; }

ul, ol { margin: 0 0 12px; padding-left: 22px; }
li + li { margin-top: 6px; }
p { margin: 0 0 12px; }

.note { color: var(--muted); font-size: 0.93rem; }

.tag {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--danger);
  margin-bottom: 6px;
}

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

table { width: 100%; border-collapse: collapse; font-size: 0.95rem; }
th, td { text-align: left; vertical-align: top; padding: 10px 12px 10px 0; border-bottom: 1px solid var(--line); }
th { color: var(--muted); font-weight: 600; white-space: nowrap; }

.toc ol { columns: 2; column-gap: 28px; margin: 0; }
.toc li { break-inside: avoid; }

.links { display: grid; grid-template-columns: repeat(auto-fit, minmax(210px, 1fr)); gap: 14px; margin-top: 22px; }

.link-card {
  display: block;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 18px 20px;
  color: var(--text);
  text-decoration: none;
}

.link-card:hover { border-color: var(--accent); }
.link-card strong { display: block; font-size: 1.05rem; margin-bottom: 4px; }
.link-card span { color: var(--muted); font-size: 0.93rem; }

.site-footer {
  margin-top: 36px;
  padding: 22px 0 34px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.9rem;
}

.site-footer nav { display: flex; flex-wrap: wrap; gap: 4px 16px; margin-top: 8px; }

@media (max-width: 560px) {
  .toc ol { columns: 1; }
  .card { padding: 18px; }
}