:root { --bg:#0f172a; --fg:#e2e8f0; --primary:#2563eb; --surface:#1e293b; --rule:#334155; --muted:#8899aa; --accent:#f59e0b; }
* { margin:0; padding:0; box-sizing:border-box; }
body { background:var(--bg); color:var(--fg); font-family:-apple-system,"PingFang SC","Microsoft YaHei",sans-serif; line-height:1.6; }
a { color:var(--primary); text-decoration:none; }
.nav { position:sticky; top:0; z-index:50; background:var(--bg); border-bottom:1px solid var(--rule); display:flex; align-items:center; justify-content:space-between; padding:14px 24px; }
.nav .logo { font-weight:700; font-size:18px; color:var(--fg); }
.nav .logo span { color:var(--primary); }
.nav .links a { margin-left:18px; color:var(--muted); font-size:14px; }
.nav .links a:hover { color:var(--fg); }
.nav .links .active { color:var(--primary); font-weight:600; }
.lang-btn { background:none; border:1px solid var(--rule); color:var(--fg); padding:5px 12px; border-radius:6px; cursor:pointer; font-size:13px; margin-left:12px; }