*{box-sizing:border-box}html,body{margin:0;background:#000;color:#e5e5e5;font-family:Inter,system-ui,sans-serif}
.layout{display:flex;min-height:100vh}
.sidebar{width:260px;border-right:1px solid #222;padding:24px;position:sticky;top:0;height:100vh;overflow:auto;background:#000}
.brand a{color:#fff;text-decoration:none;font-weight:600;font-size:14px}
.label{margin-top:24px;color:#666;font-size:11px;letter-spacing:1px}
nav{margin-top:12px;display:flex;flex-direction:column;gap:8px}
nav a{color:#aaa;text-decoration:none;font-size:13px}
nav a:hover{color:#fff}
.main{flex:1;max-width:860px;margin:0 auto;padding:40px 32px}
.topbar{display:flex;justify-content:flex-end;gap:12px;margin-bottom:24px}
.download{background:#1a1a1a;border:1px solid #333;color:#fff;padding:6px 14px;border-radius:999px;text-decoration:none;font-size:13px}
#theme{background:#111;border:1px solid #333;color:#fff;border-radius:999px;padding:6px 10px;cursor:pointer}
.content h1{font-size:32px;line-height:1.1;margin:8px 0}
.content h2{font-size:24px;margin-top:48px;border-top:1px solid #222;padding-top:24px}
.content h3{font-size:16px;margin-top:32px;color:#fff}
.content p{color:#aaa;line-height:1.6}
.content ul.lessons{list-style:none;padding:0}
.content ul.lessons li{background:#0a0a0a;border:1px solid #1a1a1a;border-radius:12px;padding:16px;margin:12px 0;line-height:1.6;color:#ccc}
.content ul.lessons li strong{color:#fff}
.content ul.lessons li a{color:#888;text-decoration:underline}
.content ul.lessons li em{color:#666;font-style:normal;font-size:12px}
.content ul.toc{list-style:none;padding:0}
.content ul.toc li a{color:#aaa;text-decoration:none}
hr{border:none;border-top:1px solid #222;margin:40px 0}
@media(max-width:800px){.sidebar{display:none}.main{padding:20px}}