:root{--card:rgba(15,23,42,.88);--line:rgba(125,211,252,.24);--text:#edf7ff;--muted:#a6bbcf;--accent:#38bdf8;--violet:#a78bfa}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;color:var(--text);font-family:Inter,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",Arial,sans-serif;line-height:1.72;background:radial-gradient(circle at 12% 8%,rgba(56,189,248,.18),transparent 30%),radial-gradient(circle at 88% 16%,rgba(167,139,250,.16),transparent 34%),linear-gradient(135deg,#050816 0%,#08111f 50%,#020617 100%)}
body:before{content:"";position:fixed;inset:0;pointer-events:none;background-image:linear-gradient(rgba(125,211,252,.04) 1px,transparent 1px),linear-gradient(90deg,rgba(125,211,252,.04) 1px,transparent 1px);background-size:40px 40px}
.site-shell{max-width:1220px;margin:0 auto;padding:30px 18px 56px}
.hero{border:1px solid var(--line);border-radius:28px;padding:34px;background:linear-gradient(135deg,rgba(15,23,42,.92),rgba(2,6,23,.76));box-shadow:0 24px 80px rgba(0,0,0,.36),inset 0 0 42px rgba(56,189,248,.05);overflow:hidden;position:relative}
.hero:after{content:"атом • ядро • электроны • периоды • свойства элементов";position:absolute;right:-54px;bottom:14px;color:rgba(56,189,248,.12);font-size:38px;font-weight:900;letter-spacing:.04em;transform:rotate(-4deg);white-space:nowrap}
.badge{display:none}
.hero h1{margin:0;font-size:clamp(34px,5vw,60px);line-height:1.04;letter-spacing:-.04em}
.hero p{display:none}
.layout{display:grid;grid-template-columns:300px minmax(0,1fr);gap:22px;margin-top:22px}
.sidebar{position:sticky;top:18px;align-self:start;border:1px solid var(--line);border-radius:22px;background:rgba(2,6,23,.76);padding:16px;box-shadow:0 12px 42px rgba(0,0,0,.28)}
.sidebar h2{margin:0 0 12px;color:#bae6fd;font-size:15px;letter-spacing:.08em;text-transform:uppercase}
.navlink{display:block;padding:9px 11px;color:var(--text);text-decoration:none;border:1px solid transparent;border-radius:14px}
.navlink:hover{color:#7dd3fc;background:rgba(56,189,248,.09);border-color:rgba(56,189,248,.25)}
.page-card{border:1px solid var(--line);border-radius:26px;padding:30px;background:var(--card);box-shadow:0 18px 60px rgba(0,0,0,.30);overflow:hidden}
.page-card h1{margin:0 0 18px;font-size:clamp(30px,4vw,48px);line-height:1.12}
.page-card h2{margin-top:30px;padding-top:14px;border-top:1px solid rgba(125,211,252,.18);color:#bae6fd}
.page-card h3{color:#ddd6fe;margin-top:24px}
p{margin:13px 0} a{color:#7dd3fc;text-decoration:none;border-bottom:1px solid rgba(125,211,252,.35)} a:hover{color:#e0f2fe;border-bottom-color:#e0f2fe}
.unresolved-link{color:#fbbf24}.content-list{padding-left:24px}.content-list li{margin:8px 0}
code{color:#bbf7d0;background:rgba(52,211,153,.10);border:1px solid rgba(52,211,153,.22);padding:2px 6px;border-radius:7px}
pre{overflow:auto;padding:16px;border-radius:16px;border:1px solid rgba(125,211,252,.18);background:rgba(2,6,23,.70)}
blockquote{margin:18px 0;padding:14px 18px;border-left:4px solid var(--accent);background:rgba(56,189,248,.08);border-radius:12px}
.math-block{overflow-x:auto;margin:18px 0;padding:16px;border:1px solid rgba(56,189,248,.25);background:rgba(15,23,42,.72);border-radius:16px}
.table-scroll{overflow-x:auto;margin:18px 0} table{border-collapse:collapse;min-width:520px;width:100%;background:rgba(15,23,42,.50)} td,th{border:1px solid rgba(125,211,252,.20);padding:10px 12px} th{background:rgba(56,189,248,.12);color:#dff6ff}
.image-card{margin:22px 0;padding:22px;border:1px solid rgba(125,211,252,.24);border-radius:20px;background:rgba(2,6,23,.32);text-align:center}
.image-card img{display:block;width:min(100%, 980px);max-width:100%;max-height:none;margin:0 auto;border-radius:14px}
.image-card.wide img{width:100%;max-width:100%;max-height:none}
.image-card figcaption{margin-top:10px;color:var(--muted);font-size:14px}
.image-missing{display:none}
.grid-cards{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:14px;margin-top:20px}.tile{display:block;border:1px solid rgba(125,211,252,.24);border-radius:18px;padding:16px;background:rgba(15,23,42,.55);min-height:130px}.tile h3{margin:0 0 8px;color:#bae6fd}.tile p{color:var(--muted)}
.back{display:inline-flex;margin-bottom:18px;color:#e0f2fe;background:rgba(56,189,248,.08);border:1px solid rgba(56,189,248,.30);border-radius:999px;padding:8px 12px}
@media(max-width:900px){.layout{grid-template-columns:1fr}.sidebar{position:static}.page-card{padding:22px}}