:root{--bg:#0a0a0f;--bg2:#111118;--card:#16161f;--text:#f0f0f5;--muted:#a0a0b8;--dim:#6a6a80;--accent:#6366f1;--accent2:#818cf8;--cyan:#06b6d4;--border:rgba(255,255,255,.08);--grad:linear-gradient(135deg,#6366f1,#06b6d4)}
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{font-family:'Inter',-apple-system,BlinkMacSystemFont,sans-serif;background:var(--bg);color:var(--text);line-height:1.75;-webkit-font-smoothing:antialiased}
a{color:inherit;text-decoration:none}
.wrap{max-width:760px;margin:0 auto;padding:0 24px}
.site-header{position:sticky;top:0;z-index:20;background:rgba(10,10,15,.85);backdrop-filter:blur(14px);border-bottom:1px solid var(--border)}
.site-header .wrap{display:flex;align-items:center;justify-content:space-between;height:64px;max-width:1100px}
.brand{font-family:'Space Grotesk',sans-serif;font-weight:700;font-size:1.05rem;letter-spacing:-.02em}
.brand span{background:var(--grad);-webkit-background-clip:text;background-clip:text;-webkit-text-fill-color:transparent}
.nav-back{font-size:.9rem;color:var(--muted);transition:color .2s}
.nav-back:hover{color:var(--text)}
main{padding:48px 0 80px}
.breadcrumb{font-size:.82rem;color:var(--dim);margin-bottom:28px;display:flex;gap:8px;flex-wrap:wrap}
.breadcrumb a:hover{color:var(--accent2)}
.part-label{font-family:'Space Grotesk',sans-serif;text-transform:uppercase;letter-spacing:.14em;font-size:.75rem;color:var(--cyan);font-weight:600;margin-bottom:14px}
h1{font-family:'Space Grotesk',sans-serif;font-weight:700;font-size:clamp(2rem,5vw,2.9rem);line-height:1.1;letter-spacing:-.02em;margin-bottom:16px}
.meta{color:var(--dim);font-size:.85rem;margin-bottom:40px;padding-bottom:28px;border-bottom:1px solid var(--border)}
.body p{margin:0 0 1.4em;font-size:1.075rem;color:#dcdce6}
.body p:first-of-type::first-letter{font-family:'Space Grotesk',sans-serif;font-size:3.1rem;font-weight:700;float:left;line-height:.9;padding:4px 12px 0 0;background:var(--grad);-webkit-background-clip:text;background-clip:text;-webkit-text-fill-color:transparent}
.pager{display:flex;justify-content:space-between;gap:16px;margin-top:56px;padding-top:32px;border-top:1px solid var(--border)}
.pager a{flex:1;padding:18px 20px;background:var(--card);border:1px solid var(--border);border-radius:12px;transition:.25s;min-width:0}
.pager a:hover{border-color:var(--accent);transform:translateY(-2px)}
.pager .dir{font-size:.72rem;text-transform:uppercase;letter-spacing:.1em;color:var(--dim);margin-bottom:5px}
.pager .t{font-weight:600;font-size:.95rem;color:var(--text);white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.pager .next{text-align:right}
.pager .spacer{background:none;border:none;pointer-events:none}
.cta{margin-top:48px;padding:28px;background:linear-gradient(135deg,rgba(99,102,241,.12),rgba(6,182,212,.08));border:1px solid var(--border);border-radius:16px;text-align:center}
.cta h3{font-family:'Space Grotesk',sans-serif;font-size:1.15rem;margin-bottom:8px}
.cta p{color:var(--muted);font-size:.9rem;margin-bottom:18px}
.btn{display:inline-block;padding:13px 26px;background:var(--grad);color:#fff;border-radius:10px;font-weight:600;font-size:.92rem;transition:.25s}
.btn:hover{transform:translateY(-2px);box-shadow:0 10px 30px rgba(99,102,241,.35)}
.site-footer{border-top:1px solid var(--border);padding:36px 0;color:var(--dim);font-size:.82rem;text-align:center}
.site-footer a{color:var(--muted)}.site-footer a:hover{color:var(--text)}
/* hub */
.hub-hero{text-align:center;padding:20px 0 8px}
.hub-hero .sub{color:var(--muted);font-size:1.1rem;max-width:640px;margin:18px auto 0}
.toc{margin-top:48px}
.toc-part{font-family:'Space Grotesk',sans-serif;text-transform:uppercase;letter-spacing:.14em;font-size:.78rem;color:var(--cyan);font-weight:600;margin:36px 0 14px;padding-bottom:10px;border-bottom:1px solid var(--border)}
.toc-item{display:block;padding:18px 22px;background:var(--card);border:1px solid var(--border);border-radius:12px;margin-bottom:12px;transition:.22s}
.toc-item:hover{border-color:var(--accent);transform:translateX(4px)}
.toc-item .n{font-family:'Space Grotesk',sans-serif;color:var(--accent2);font-weight:700;font-size:.8rem;letter-spacing:.05em}
.toc-item .tt{font-weight:600;font-size:1.08rem;margin:4px 0 5px}
.toc-item .ex{color:var(--muted);font-size:.9rem;line-height:1.55}
@media(max-width:560px){.pager .t{font-size:.82rem}.body p:first-of-type::first-letter{font-size:2.6rem}}