:root{--bg:#07090f;--bg-subtle:#131926;--bg-translucent:rgba(7,9,15,.7);--fg:#e6e9ef;--fg-muted:#97a2b4;--border:#2b3448;--accent:#5b8cff;--accent-2:#a78bfa;--accent-fg:#fff;--card:#131926;--grid-line:hsla(0,0%,100%,.045);--glow-1:rgba(91,140,255,.18);--glow-2:rgba(167,139,250,.14);color-scheme:dark}*{box-sizing:border-box}body,html{padding:0;margin:0}body{background-color:var(--bg);background-image:radial-gradient(900px 500px at 12% 0,var(--glow-1),transparent 60%),radial-gradient(700px 400px at 92% 0,var(--glow-2),transparent 60%),linear-gradient(var(--grid-line) 1px,transparent 1px),linear-gradient(90deg,var(--grid-line) 1px,transparent 1px);background-size:100% 900px,100% 900px,44px 44px,44px 44px;background-repeat:no-repeat,no-repeat,repeat,repeat;background-position:top,top,top,top;color:var(--fg);font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Inter,Roboto,sans-serif;line-height:1.5;min-height:100vh}a{color:inherit}.container{max-width:1100px;margin:0 auto;padding:0 24px}.card{background:var(--card);border:1px solid var(--border);border-radius:12px;box-shadow:0 1px 2px rgba(15,23,42,.04),0 8px 24px rgba(15,23,42,.05);transition:transform .15s ease,box-shadow .15s ease}a.card:hover{transform:translateY(-2px);box-shadow:0 4px 8px rgba(15,23,42,.06),0 16px 32px rgba(15,23,42,.08)}.btn{display:inline-flex;align-items:center;gap:8px;padding:12px 22px;border-radius:8px;font-weight:600;text-decoration:none;border:1px solid transparent;cursor:pointer;font-size:15px;transition:transform .15s ease,box-shadow .15s ease,border-color .15s ease}.btn-primary{background:linear-gradient(135deg,var(--accent),var(--accent-2));color:var(--accent-fg);box-shadow:0 4px 14px rgba(37,99,235,.28)}.btn-primary:hover{transform:translateY(-1px);box-shadow:0 6px 20px rgba(37,99,235,.36)}.btn-secondary{background:var(--card);color:var(--fg);border-color:var(--border)}.btn-secondary:hover{border-color:var(--accent)}.skip-link{position:absolute;left:16px;top:-100px;z-index:100;padding:10px 16px;border-radius:8px;background:var(--accent);color:var(--accent-fg);font-weight:600;text-decoration:none}.skip-link:focus{top:12px}:focus-visible{outline:2px solid var(--accent);outline-offset:3px}main:focus{outline:none}section[id]{scroll-margin-top:80px}@media (max-width:560px){.nav-link{display:none}.hero-title{font-size:34px!important}}.box-tabs,.topic-tabs{display:grid;grid-template-columns:repeat(3,1fr);grid-gap:10px;gap:10px}.topic-tab{position:relative;display:flex}.topic-tab input{position:absolute;opacity:0;inset:0;margin:0;cursor:pointer}.box-tab,.topic-tab span{flex:1 1;display:flex;align-items:center;justify-content:center;text-align:center;min-height:56px;padding:8px 12px;border:1px solid var(--border);border-radius:10px;background:var(--card);color:var(--fg-muted);font-size:15px;line-height:1.3;font-family:inherit;cursor:pointer;transition:border-color .15s ease,background .15s ease,color .15s ease}.box-tab:hover,.topic-tab:hover span{border-color:var(--accent)}.box-tab[aria-pressed=true],.topic-tab input:checked+span{border-color:var(--accent);background:rgba(91,140,255,.24);color:var(--fg);font-weight:600}.topic-tab input:focus-visible+span{outline:2px solid var(--accent);outline-offset:3px}@media (max-width:480px){.box-tabs,.topic-tabs{grid-template-columns:1fr}.box-tab,.topic-tab span{min-height:44px}}select:invalid{color:var(--fg-muted)}select option{color:var(--fg)}