:root {
  --bg: #0a0e14;
  --bg-card: #11161f;
  --text: #e6edf3;
  --text-dim: #8b949e;
  --accent: #79c0ff;
  --border: #21262d;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-mono: "JetBrains Mono", "SF Mono", Menlo, Consolas, monospace;
}
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

.topbar {
  border-bottom: 1px solid var(--border);
  padding: 16px 28px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: rgba(10, 14, 20, 0.85);
  backdrop-filter: blur(8px);
  position: sticky;
  top: 0;
  z-index: 10;
}
.topbar__brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 600;
  color: var(--text);
}
.topbar__brand img {
  height: 38px;
  background: #fff;
  padding: 5px 12px;
  border-radius: 8px;
  box-shadow: 0 4px 14px rgba(0, 0, 0, 0.25);
}
.topbar__nav a {
  color: var(--text-dim);
  margin-left: 22px;
  font-size: 14px;
}
.topbar__nav a:hover { color: var(--accent); text-decoration: none; }

.wrap {
  max-width: 760px;
  margin: 0 auto;
  padding: 56px 28px 80px;
}
.crumb {
  color: var(--text-dim);
  font-size: 13px;
  margin-bottom: 24px;
  font-family: var(--font-mono);
}
.crumb a { color: var(--text-dim); }
.crumb a:hover { color: var(--accent); }

article h1 {
  font-size: 34px;
  line-height: 1.25;
  margin: 0 0 18px;
  font-weight: 700;
  letter-spacing: -0.01em;
}
.meta {
  color: var(--text-dim);
  font-size: 13.5px;
  margin-bottom: 36px;
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
}
.meta span { font-family: var(--font-mono); }

article h2 {
  font-size: 22px;
  line-height: 1.4;
  margin: 44px 0 14px;
  font-weight: 600;
  border-left: 3px solid var(--accent);
  padding-left: 12px;
}
article h3 {
  font-size: 17px;
  margin: 28px 0 10px;
  font-weight: 600;
}
article p { margin: 14px 0; }
article ul, article ol { padding-left: 24px; }
article li { margin: 6px 0; }
article strong { color: var(--text); font-weight: 600; }
article blockquote {
  margin: 18px 0;
  padding: 14px 18px;
  border-left: 3px solid var(--border);
  background: var(--bg-card);
  color: var(--text-dim);
  border-radius: 0 8px 8px 0;
}
article code {
  font-family: var(--font-mono);
  font-size: 0.92em;
  padding: 2px 6px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 4px;
}
article hr {
  border: 0;
  border-top: 1px solid var(--border);
  margin: 36px 0;
}
article table {
  width: 100%;
  border-collapse: collapse;
  margin: 18px 0;
  font-size: 14.5px;
}
article th, article td {
  border-bottom: 1px solid var(--border);
  padding: 10px 12px;
  text-align: left;
}
article th {
  color: var(--text-dim);
  font-weight: 500;
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.lead {
  font-size: 17px;
  color: var(--text-dim);
  line-height: 1.8;
  margin: 0 0 26px;
  padding: 16px 18px;
  background: var(--bg-card);
  border-left: 3px solid var(--accent);
  border-radius: 0 8px 8px 0;
}

.cta-box {
  margin: 44px 0 12px;
  padding: 26px;
  background: linear-gradient(135deg, rgba(121, 192, 255, 0.06), rgba(121, 192, 255, 0));
  border: 1px solid var(--border);
  border-radius: 12px;
  text-align: center;
}
.cta-box h3 {
  border: 0;
  padding: 0;
  margin: 0 0 10px;
  font-size: 18px;
}
.btn {
  display: inline-block;
  padding: 10px 22px;
  border-radius: 8px;
  font-size: 14.5px;
  font-weight: 500;
  margin: 4px 6px;
  border: 1px solid var(--border);
  color: var(--text);
}
.btn--primary {
  background: var(--accent);
  color: #0a0e14;
  border-color: var(--accent);
}
.btn--primary:hover { background: #a5d6ff; text-decoration: none; }
.btn--ghost:hover { border-color: var(--accent); color: var(--accent); text-decoration: none; }

.related {
  margin-top: 50px;
  padding-top: 26px;
  border-top: 1px solid var(--border);
}
.related h3 {
  margin: 0 0 14px;
  font-size: 14px;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-weight: 500;
}
.related ul {
  list-style: none;
  padding: 0;
  margin: 0;
}
.related li { margin: 8px 0; }

.footer {
  border-top: 1px solid var(--border);
  padding: 28px;
  text-align: center;
  color: var(--text-dim);
  font-size: 13px;
}

/* Article index */
.hub-head { text-align: center; margin-bottom: 48px; }
.hub-head h1 { font-size: 36px; margin: 0 0 12px; }
.hub-head p { color: var(--text-dim); font-size: 16px; margin: 0; }
.hub-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 18px; }
.hub-card {
  display: block;
  padding: 22px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  transition: border-color 0.2s, transform 0.2s;
  color: var(--text);
}
.hub-card:hover { border-color: var(--accent); transform: translateY(-2px); text-decoration: none; }
.hub-card .tag { font-family: var(--font-mono); font-size: 11.5px; color: var(--accent); text-transform: uppercase; letter-spacing: 0.04em; }
.hub-card h2 { border: 0; padding: 0; font-size: 17px; margin: 8px 0 8px; line-height: 1.4; }
.hub-card p { margin: 0; color: var(--text-dim); font-size: 13.5px; line-height: 1.7; }

@media (max-width: 600px) {
  .topbar { padding: 14px 18px; }
  .topbar__nav a { margin-left: 14px; font-size: 13px; }
  .wrap { padding: 36px 20px 60px; }
  article h1 { font-size: 26px; }
  article h2 { font-size: 19px; }
  .hub-head h1 { font-size: 26px; }
}