:root {
  --ink: #1c1d21;
  --ink-soft: #52545c;
  --line: #e8e8ec;
  --accent: #5b5fef;
  --accent-soft: #eef0ff;
  --shadow: 0 2px 8px rgba(28, 29, 33, 0.05), 0 10px 30px rgba(28, 29, 33, 0.06);
  --radius: 16px;
  --max-width: 760px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: #ffffff;
  color: var(--ink);
  font-family: -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji";
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 20px;
}

/* Header */
.site-header {
  border-bottom: 1px solid var(--line);
  position: sticky;
  top: 0;
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: saturate(180%) blur(8px);
  z-index: 10;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 1.05rem;
}

.brand-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border-radius: 9px;
  background: var(--accent);
  color: #fff;
  font-weight: 800;
  font-size: 1rem;
}

.top-nav {
  display: flex;
  gap: 20px;
}

.top-nav a {
  color: var(--ink-soft);
  text-decoration: none;
  font-size: 0.92rem;
  font-weight: 500;
}

.top-nav a:hover {
  color: var(--accent);
}

/* Main document card */
main {
  padding: 48px 20px 64px;
}

.doc-card {
  background: #ffffff;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 40px 36px 44px;
}

h1 {
  margin: 0 0 6px;
  font-size: 2rem;
  letter-spacing: -0.02em;
}

.meta-line {
  margin: 0 0 28px;
  color: var(--ink-soft);
  font-size: 0.9rem;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--line);
}

h2 {
  font-size: 1.15rem;
  margin: 34px 0 10px;
  letter-spacing: -0.01em;
}

p {
  margin: 0 0 14px;
  color: #303138;
}

ul {
  margin: 0 0 14px;
  padding-left: 22px;
  color: #303138;
}

li {
  margin-bottom: 8px;
}

code {
  background: var(--accent-soft);
  color: var(--accent);
  padding: 2px 6px;
  border-radius: 6px;
  font-size: 0.88em;
}

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

/* Footer */
.site-footer {
  border-top: 1px solid var(--line);
  padding: 28px 0;
}

.site-footer p {
  margin: 0;
  color: var(--ink-soft);
  font-size: 0.85rem;
  text-align: center;
}

/* Responsive */
@media (max-width: 600px) {
  .doc-card {
    padding: 28px 20px 32px;
    border-radius: 12px;
  }

  h1 {
    font-size: 1.6rem;
  }

  .top-nav {
    gap: 14px;
  }

  .top-nav a {
    font-size: 0.85rem;
  }
}

/* Dark mode support (system preference) */
@media (prefers-color-scheme: dark) {
  :root {
    --ink: #eef0f4;
    --ink-soft: #a7a9b4;
    --line: #2a2b31;
    --accent: #8b8ffb;
    --accent-soft: #23233a;
    --shadow: 0 2px 8px rgba(0, 0, 0, 0.3), 0 10px 30px rgba(0, 0, 0, 0.35);
  }

  body {
    background: #0f1013;
  }

  .site-header {
    background: rgba(15, 16, 19, 0.85);
  }

  .doc-card {
    background: #16171c;
  }

  p, ul, li {
    color: #cfd1d9;
  }
}