:root{color-scheme:light dark;--bg:#f5f5f7;--card:#fff;--fg:#1d1d1f;--muted:#6e6e73;--accent:#0071e3;--line:#d2d2d7}
@media (prefers-color-scheme:dark){:root{--bg:#000;--card:#1c1c1e;--fg:#f5f5f7;--muted:#a1a1a6;--accent:#2997ff;--line:#38383a}}
*{box-sizing:border-box}
body{margin:0;background:var(--bg);color:var(--fg);font:17px/1.6 -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;-webkit-text-size-adjust:100%}
header,footer{max-width:760px;margin:0 auto;padding:20px}
header{display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:8px;border-bottom:1px solid var(--line)}
header .brand{font-weight:600;font-size:20px;color:var(--fg);text-decoration:none}
nav a{margin-left:16px;color:var(--accent);text-decoration:none}
nav a:first-child{margin-left:0}
main{max-width:760px;margin:24px auto;padding:0 20px}
.card{background:var(--card);border-radius:18px;padding:24px 28px;box-shadow:0 2px 12px rgba(0,0,0,.06)}
h1{font-size:30px;line-height:1.2;margin:0 0 12px}
h2{font-size:20px;margin:28px 0 8px}
a{color:var(--accent)}
.muted{color:var(--muted)}
footer{border-top:1px solid var(--line);color:var(--muted);font-size:14px;margin-top:32px}
footer a{color:var(--muted)}
@media (max-width:480px){.card{padding:20px}h1{font-size:26px}}