:root {
  --bg: #0a0a0f; --bg2: #12121a; --bg3: #1a1a28;
  --tx: #e0e0e8; --tx2: #a0a0b0; --ac: #7c5ce7; --gl: #c9a84c;
  --bd: #2a2a3a; --mw: 860px;
}
*{margin:0;padding:0;box-sizing:border-box}
html{font-size:17px;scroll-behavior:smooth}
body{font-family:system-ui,-apple-system,sans-serif;background:var(--bg);color:var(--tx);line-height:1.7;display:flex;flex-direction:column;min-height:100vh}
.site-nav{background:var(--bg2);border-bottom:1px solid var(--bd);position:sticky;top:0;z-index:1000}
.nav-container{max-width:var(--mw);margin:0 auto;padding:0 1.5rem;display:flex;align-items:center;height:56px;gap:1.5rem}
.site-title{font-weight:700;font-size:1.05rem;color:var(--gl);text-decoration:none;white-space:nowrap}
.nav-links{display:flex;gap:.25rem;align-items:center;font-size:.82rem}
.nav-links a{color:var(--tx2);text-decoration:none;padding:.35rem .6rem;border-radius:4px;white-space:nowrap;transition:.2s}
.nav-links a:hover{color:var(--tx);background:var(--bg3)}
.nav-dropdown{position:relative}.nav-dropdown>span{color:var(--tx2);padding:.35rem .6rem;cursor:pointer;border-radius:4px;font-size:.82rem}
.nav-dropdown>span:hover{color:var(--tx);background:var(--bg3)}
.dropdown-content{display:none;position:absolute;top:100%;left:0;background:var(--bg2);border:1px solid var(--bd);border-radius:6px;min-width:200px;z-index:1001;padding:.4rem 0;box-shadow:0 8px 24px rgba(0,0,0,.5)}
.nav-dropdown:hover .dropdown-content{display:block}
.dropdown-content a{display:block;padding:.4rem 1rem}
.nav-toggle{display:none;background:none;border:none;color:var(--tx);font-size:1.2rem;cursor:pointer}
.content{flex:1;max-width:var(--mw);margin:0 auto;padding:2rem 1.5rem 4rem;width:100%}
h1,h2,h3,h4{color:var(--tx);line-height:1.3;margin-top:2rem;margin-bottom:.75rem}
h1{font-size:2rem;border-bottom:2px solid var(--ac);padding-bottom:.5rem;margin-bottom:1.5rem;color:var(--gl)}
h2{font-size:1.45rem;border-bottom:1px solid var(--bd);padding-bottom:.35rem}
h3{font-size:1.2rem}p{margin-bottom:1rem}a{color:var(--ac);text-decoration:none}a:hover{text-decoration:underline}
strong{color:var(--tx)}blockquote{border-left:3px solid var(--ac);padding:.75rem 1.25rem;margin:1.5rem 0;background:var(--bg2);border-radius:0 6px 6px 0;color:var(--tx2);font-style:italic}
code{background:#16162a;padding:.15rem .4rem;border-radius:4px;font-family:'Cascadia Code','Fira Code',Consolas,monospace;font-size:.88em;color:var(--gl)}
pre{background:#16162a;padding:1rem 1.25rem;border-radius:8px;overflow-x:auto;margin:1rem 0;border:1px solid var(--bd);font-size:.85rem}
pre code{background:none;padding:0}
table{width:100%;border-collapse:collapse;margin:1.5rem 0;font-size:.92rem}
thead{background:var(--bg3)}th{padding:.6rem .8rem;text-align:left;border-bottom:2px solid var(--bd);font-weight:600;color:var(--gl)}
td{padding:.5rem .8rem;border-bottom:1px solid var(--bd)}tr:hover{background:rgba(124,92,231,.08)}
ul,ol{margin:.75rem 0 .75rem 1.5rem}li{margin-bottom:.35rem}
.definition,.theorem,.corollary,.lemma,.example,.proof,.insight{margin:1.25rem 0;padding:1rem 1.25rem;border-radius:8px;border-left:4px solid var(--ac);background:var(--bg2)}
.definition{border-left-color:#4a90d9}.theorem{border-left-color:var(--gl)}.corollary{border-left-color:#e8845c}
.lemma{border-left-color:#5cb88d}.example{border-left-color:#9e7cf0}.proof{border-left-color:#6a6a8a}
.insight{border-left-color:var(--ac);background:rgba(124,92,231,.08)}
.definition .label,.theorem .label,.corollary .label,.lemma .label,.example .label{font-weight:700;font-size:.8rem;text-transform:uppercase;letter-spacing:.05em;margin-bottom:.3rem;color:#606078}
.chapter-nav{display:flex;justify-content:space-between;margin-top:3rem;padding-top:1.5rem;border-top:1px solid var(--bd)}
.chapter-nav a{padding:.5rem 1rem;border:1px solid var(--bd);border-radius:6px;transition:.2s}
.chapter-nav a:hover{background:var(--bg3);text-decoration:none}
.hero{text-align:center;padding:3rem 1rem 2rem}
.hero h1{font-size:2.4rem;border:none;margin-bottom:.5rem}
.hero .subtitle{font-size:1.15rem;color:var(--tx2);margin-bottom:2rem}
.hero .cta{display:flex;gap:1rem;justify-content:center;flex-wrap:wrap}
.hero .cta a{display:inline-block;padding:.7rem 1.5rem;border-radius:8px;background:var(--ac);color:#fff;font-weight:600;transition:.2s}
.hero .cta a:hover{background:#5a3fb8;text-decoration:none}
.hero .cta a.secondary{background:var(--bg3);border:1px solid var(--bd)}
.toc-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:1.25rem;margin:2rem 0}
.toc-card{background:var(--bg2);border:1px solid var(--bd);border-radius:10px;padding:1.25rem;transition:.2s;text-decoration:none;color:var(--tx);display:block}
.toc-card:hover{border-color:var(--ac);transform:translateY(-2px);text-decoration:none}
.toc-card h3{margin-top:0;font-size:1.05rem;color:var(--gl)}
.toc-card p{font-size:.88rem;color:var(--tx2);margin-bottom:0}
.toc-card .chapter-num{font-size:.72rem;color:#606078;text-transform:uppercase;letter-spacing:.08em}
.site-footer{background:var(--bg2);border-top:1px solid var(--bd);padding:1.5rem;text-align:center;font-size:.82rem;color:#606078}
.site-footer a{color:var(--tx2)}
.features{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:1.5rem;margin:2.5rem 0}
.feature{text-align:center;padding:1rem}
.feature .icon{font-size:2rem;margin-bottom:.5rem}
.feature h3{margin-top:0;font-size:1rem}.feature p{font-size:.85rem;color:var(--tx2)}
::-webkit-scrollbar{width:8px;height:8px}::-webkit-scrollbar-track{background:var(--bg)}
::-webkit-scrollbar-thumb{background:var(--bg3);border-radius:4px}::-webkit-scrollbar-thumb:hover{background:var(--bd)}
@media(max-width:768px){html{font-size:15px}.nav-links{display:none;flex-direction:column;position:absolute;top:56px;left:0;width:100%;background:var(--bg2);border-bottom:1px solid var(--bd);padding:.5rem 1.5rem}.nav-links.active{display:flex}.nav-toggle{display:block}.nav-dropdown .dropdown-content{position:static;box-shadow:none;border:none;padding-left:1rem}.hero h1{font-size:1.8rem}.toc-grid{grid-template-columns:1fr}}