/* Base Reset */
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; font-family: system-ui, -apple-system, Segoe UI, Roboto, Inter, Arial, sans-serif; line-height: 1.65; }
:root {
  --bg: #ffffff;
  --fg: #111111;
  --muted: #666666;
  --link: #0b66ff;
  --link-visited: #6b2cff;
  --border: #e5e5e5;
  --card: #fafafa;
  --accent: #0b66ff;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0c0d10;
    --fg: #e9eaee;
    --muted: #a4a7b0;
    --link: #7aa2ff;
    --link-visited: #b28cff;
    --border: #23252c;
    --card: #13151b;
    --accent: #7aa2ff;
  }
}
body { background: var(--bg); color: var(--fg); }
a { color: var(--link); }
a:visited { color: var(--link-visited); }
.container { max-width: 920px; margin: 0 auto; padding: 24px; }
header, footer { border-bottom: 1px solid var(--border); }
footer { border-top: 1px solid var(--border); border-bottom: none; }
.site-title { font-weight: 800; letter-spacing: -0.02em; font-size: 1.2rem; margin: 0; }
nav a { margin-right: 14px; text-decoration: none; font-weight: 600; }
nav a:hover { text-decoration: underline; }
.hero { padding: 32px 0 8px; }
h1 { font-size: 2rem; line-height: 1.2; margin: 0 0 12px; letter-spacing:-0.01em; }
h2 { font-size: 1.35rem; line-height: 1.25; margin-top: 28px; }
h3 { font-size: 1.1rem; margin-top: 20px; }
p { margin: 12px 0; color: var(--fg); }
.muted { color: var(--muted); }
.card { background: var(--card); border: 1px solid var(--border); border-radius: 12px; padding: 16px; margin: 12px 0; }
.badge { display: inline-block; padding: 2px 8px; border-radius: 999px; border: 1px solid var(--border); font-size: 12px; }
.grid { display: grid; gap: 14px; }
.grid-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
@media (max-width: 720px) { .grid-2 { grid-template-columns: 1fr; } }
.table { width: 100%; border-collapse: collapse; margin: 12px 0; }
.table th, .table td { border-bottom: 1px solid var(--border); padding: 8px 6px; text-align: left; }
.kicker { text-transform: uppercase; letter-spacing: .12em; font-weight: 700; font-size: 12px; color: var(--muted); }
code, pre { background: var(--card); border: 1px solid var(--border); border-radius: 10px; padding: 2px 4px; }
.footer-links a { margin-right: 12px; }
.meta { font-size: 14px; color: var(--muted); }
.proof-level { font-weight: 700; }
.callout { border-left: 3px solid var(--accent); padding-left: 12px; }
hr { border: none; border-top: 1px solid var(--border); margin: 24px 0; }
img { max-width: 100%; height: auto; display: block; }
.visually-hidden { position:absolute; left:-10000px; width:1px; height:1px; overflow:hidden; }