:root{--bg:#0f172a;--panel:#111827;--card:#1f2937;--text:#e5e7eb;--muted:#9ca3af;--accent:#22d3ee;--accent-2:#60a5fa}html,body{margin:0;padding:0;background:var(--bg);color:var(--text);font:16px/1.6 system-ui, -apple-system, Segoe UI, Roboto, Ubuntu, Cantarell, Noto Sans, Helvetica, Arial, "Apple Color Emoji","Segoe UI Emoji"}a{color:var(--accent);text-decoration:none}a:hover{text-decoration:underline}header{position:sticky;top:0;z-index:10;background:linear-gradient(180deg, rgba(15,23,42,.98) 70%, rgba(15,23,42,0));backdrop-filter:saturate(160%) blur(6px);border-bottom:1px solid rgba(255,255,255,.06)}.wrap{max-width:1050px;margin:0 auto;padding:20px 16px}h1{margin:4px 0 8px;font-size:clamp(24px,3.5vw,34px);line-height:1.2}.sub{color:var(--muted);margin:0 0 14px}.az{display:grid;grid-template-columns:repeat(auto-fit,minmax(28px,1fr));gap:6px;background:var(--panel);padding:10px;border-radius:12px}.az a{display:inline-grid;place-items:center;height:34px;border-radius:8px;border:1px solid rgba(255,255,255,.08);color:var(--text);background:linear-gradient(180deg, rgba(255,255,255,.02), rgba(255,255,255,.01));transition:transform .05s ease, background .2s ease, border-color .2s ease}.az a:hover{transform:translateY(-1px);border-color:rgba(34,211,238,.6);background:linear-gradient(180deg, rgba(34,211,238,.10), rgba(34,211,238,.04))}main{max-width:1050px;margin:0 auto;padding:12px 16px 40px}section.letter{scroll-margin-top:84px}.card{background:var(--card);border:1px solid rgba(255,255,255,.06);border-radius:14px;margin:22px 0;overflow:hidden}.card header{position:relative;background:linear-gradient(90deg, rgba(34,211,238,.15), rgba(96,165,250,.12));border:none}.card h2{margin:0;padding:14px 16px;font-size:22px}dl{display:grid;grid-template-columns:1fr;gap:0;border-top:1px solid rgba(255,255,255,.06)}dt{font-weight:700;padding:12px 16px;border-bottom:1px solid rgba(255,255,255,.06);background:rgba(255,255,255,.02)}dd{margin:0;padding:10px 16px 14px;color:var(--text);border-bottom:1px dashed rgba(255,255,255,.06)}.top{display:inline-block;margin:10px 16px 14px;color:var(--muted)}.top:hover{color:var(--accent-2)}@media (min-width:720px){dl{grid-template-columns:260px 1fr}dt{border-right:1px solid rgba(255,255,255,.06);border-bottom:none}dd{border-bottom:none}}footer{max-width:1050px;margin:0 auto 60px;background:var(--panel);border:1px solid rgba(255,255,255,.06);border-radius:12px;padding:14px 16px;color:var(--muted)}