:root {
  color-scheme: light dark;

  --bg: #ffffff;
  --surface: #f6f7f9;
  --text: #111418;
  --muted: #5b6775;
  --border: #d7dde6;
  --link: #0b57d0;

  --radius: 14px;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.06), 0 6px 18px rgba(0, 0, 0, 0.08);

  --maxw: 76ch;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b0d10;
    --surface: #12151b;
    --text: #e9eef6;
    --muted: #a7b4c5;
    --border: #2b3442;
    --link: #8ab4ff;

    --shadow: 0 1px 2px rgba(0, 0, 0, 0.25), 0 10px 26px rgba(0, 0, 0, 0.35);
  }
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial,
    "Apple Color Emoji", "Segoe UI Emoji";
  line-height: 1.55;
  background: radial-gradient(1200px 800px at 20% -10%, rgba(11, 87, 208, 0.12), transparent 60%),
    radial-gradient(900px 700px at 85% 10%, rgba(138, 180, 255, 0.10), transparent 55%),
    var(--bg);
  color: var(--text);
}

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

a:hover {
  text-decoration: underline;
}

.skip-link {
  position: absolute;
  left: 12px;
  top: 12px;
  padding: 10px 12px;
  border-radius: 10px;
  background: var(--surface);
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
  transform: translateY(-140%);
  transition: transform 160ms ease;
  z-index: 10;
}

.skip-link:focus {
  transform: translateY(0);
  outline: none;
}

header {
  padding: 56px 20px 18px;
}

main {
  padding: 0 20px 60px;
}

.container {
  margin: 0 auto;
  max-width: var(--maxw);
}

.card {
  background: color-mix(in oklab, var(--surface) 92%, transparent);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 22px;
}

h1 {
  font-size: clamp(1.9rem, 2.4vw + 1.1rem, 2.6rem);
  letter-spacing: -0.02em;
  line-height: 1.15;
  margin: 0 0 10px;
}

.subtitle {
  margin: 0;
  color: var(--muted);
}

.meta {
  margin-top: 12px;
  display: flex;
  flex-wrap: wrap;
  gap: 10px 14px;
  color: var(--muted);
  font-size: 0.98rem;
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 10px;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: color-mix(in oklab, var(--bg) 70%, var(--surface) 30%);
}

hr {
  border: 0;
  border-top: 1px solid var(--border);
  margin: 22px 0;
}

h2 {
  font-size: 1.28rem;
  margin: 26px 0 10px;
  letter-spacing: -0.01em;
}

h3 {
  font-size: 1.08rem;
  margin: 18px 0 8px;
}

p {
  margin: 10px 0;
}

ul {
  margin: 10px 0 10px 1.2rem;
  padding: 0;
}

li {
  margin: 6px 0;
}

.toc {
  margin-top: 14px;
}

.toc a {
  display: inline-block;
  padding: 6px 10px;
  border-radius: 10px;
  border: 1px solid var(--border);
  margin: 6px 8px 0 0;
  background: color-mix(in oklab, var(--bg) 60%, var(--surface) 40%);
}

.notice {
  border-left: 4px solid var(--link);
  padding: 10px 12px;
  border-radius: 10px;
  background: color-mix(in oklab, var(--surface) 86%, transparent);
  color: var(--text);
  margin: 14px 0;
}

.small {
  color: var(--muted);
  font-size: 0.95rem;
}

footer {
  padding: 20px;
  color: var(--muted);
}

footer .container {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
}

@media print {
  body {
    background: #fff;
  }

  .card {
    box-shadow: none;
  }

  .toc a {
    border: 0;
    padding: 0;
  }
}