:root { --bg: #ffffff; --fg: #0f172a; --muted: #475569; --line: #e2e8f0; --accent: #007aff; --card: #f1f5f9; }
@media (prefers-color-scheme: dark) { :root { --bg: #0b1220; --fg: #e5e7eb; --muted: #94a3b8; --line: #1e293b; --accent: #4da3ff; --card: #111b2e; } }
* { box-sizing: border-box; }
body { margin: 0; background: var(--bg); color: var(--fg); font: 17px/1.6 -apple-system, BlinkMacSystemFont, "SF Pro Text", "Helvetica Neue", Arial, sans-serif; }
header, main, footer { max-width: 720px; margin: 0 auto; padding: 0 20px; }
header { display: flex; align-items: center; justify-content: space-between; padding-top: 20px; padding-bottom: 14px; border-bottom: 1px solid var(--line); }
.brand { font-weight: 700; font-size: 20px; color: var(--fg); text-decoration: none; }
nav a { margin-left: 18px; color: var(--accent); text-decoration: none; font-size: 16px; }
main { padding-top: 28px; padding-bottom: 40px; }
h1 { font-size: 30px; line-height: 1.2; margin: 0 0 6px; }
h2 { font-size: 21px; margin: 34px 0 6px; }
h3 { font-size: 17px; margin: 22px 0 4px; }
p, li { color: var(--fg); }
.lead, .meta { color: var(--muted); }
.card { background: var(--card); border-radius: 14px; padding: 14px 18px; margin: 18px 0; }
ul { padding-left: 22px; }
a { color: var(--accent); }
footer { border-top: 1px solid var(--line); padding-top: 16px; padding-bottom: 36px; color: var(--muted); font-size: 15px; }