:root{
  --bg:#071321;--panel:#0d2138;--panel2:#102a46;--line:#294b68;
  --text:#f2f8ff;--muted:#afc4d8;--blue:#45c4ff;--cyan:#29e0d2;
  --green:#72efb8;--gold:#ffd166;--danger:#ff9f9f;--violet:#a78bfa
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:linear-gradient(135deg,#07111d,#0b2238);color:var(--text);font-family:Inter,Segoe UI,Arial,sans-serif;line-height:1.65}
a{color:inherit;text-decoration:none}
.container{width:min(1180px,calc(100% - 32px));margin:auto}
.site-header{position:sticky;top:0;z-index:100;background:rgba(5,14,26,.96);backdrop-filter:blur(12px);border-bottom:1px solid var(--line)}
.header-inner{min-height:66px;display:flex;align-items:center;gap:16px}
.brand{display:flex;align-items:center;gap:10px;font-weight:900}
.brand-mark{width:40px;height:40px;border-radius:11px;display:grid;place-items:center;background:linear-gradient(135deg,var(--blue),var(--cyan));color:#03111d}
.brand small{display:block;color:var(--muted);font-size:10px;letter-spacing:.08em;text-transform:uppercase}
.header-links{display:flex;gap:6px;flex:1;justify-content:center}
.header-links a{padding:8px 9px;border-radius:8px;color:#c9d8e6;font-size:12px;font-weight:800}
.header-links a:hover{background:var(--panel2);color:#fff}
.header-action{padding:9px 12px;border:1px solid #3c5f7d;border-radius:9px;background:#15314a;font-weight:800;font-size:12px}
.hero{padding:72px 0 52px;background:radial-gradient(circle at 85% 10%,rgba(69,196,255,.16),transparent 32%),radial-gradient(circle at 10% 0,rgba(41,224,210,.10),transparent 30%);border-bottom:1px solid var(--line)}
.eyebrow{color:var(--cyan);font-size:13px;font-weight:900;letter-spacing:1.4px;text-transform:uppercase}
h1{font-size:clamp(40px,6vw,68px);line-height:1.05;margin:14px 0 18px}
h2{font-size:30px;margin:0 0 14px}
h3{margin:18px 0 8px}
.lead{color:var(--muted);font-size:18px;max-width:930px}
.meta{display:flex;flex-wrap:wrap;gap:10px;margin-top:20px}
.pill{display:inline-flex;padding:7px 11px;border-radius:999px;background:#153956;color:var(--blue);font-size:12px;font-weight:850}
.layout{display:grid;grid-template-columns:250px minmax(0,1fr);gap:22px;padding:54px 0 74px}
.sidebar{position:sticky;top:82px;height:fit-content;background:var(--panel);border:1px solid var(--line);border-radius:16px;padding:18px}
.sidebar strong{display:block;margin-bottom:10px}
.sidebar a{display:block;padding:8px 10px;border-radius:8px;color:var(--muted)}
.sidebar a:hover{background:var(--panel2);color:#fff}
.section{background:var(--panel);border:1px solid var(--line);border-radius:16px;padding:24px;margin-bottom:18px}
.section p,.section li,.section td{color:#c0d0df}
.section ul,.section ol{padding-left:22px}
.code{background:#030a12;border:1px solid #31536f;border-radius:10px;padding:15px;color:#dffff0;font:14px/1.6 Consolas,monospace;overflow:auto}
.table-wrap{overflow:auto}.table{width:100%;border-collapse:collapse;min-width:680px}
.table th,.table td{padding:10px;border:1px solid var(--line);text-align:left}.table th{background:var(--panel2)}
.grid{display:grid;grid-template-columns:repeat(2,1fr);gap:16px}
.grid3{display:grid;grid-template-columns:repeat(3,1fr);gap:16px}
.card{background:var(--panel2);border:1px solid var(--line);border-radius:12px;padding:17px}
.explain{background:#0b2b45;border:1px solid #1f5678;border-left:4px solid var(--cyan);border-radius:0 10px 10px 0;padding:14px 16px;margin:14px 0}
.note{background:#231d0c;border:1px solid #6b5518;border-left:4px solid var(--gold);border-radius:0 10px 10px 0;padding:14px 16px;margin:14px 0}
.visual{width:100%;max-height:470px;object-fit:contain;background:#07111f;border:1px solid var(--line);border-radius:12px;padding:12px}
.control-panel{background:#07111f;border:1px solid var(--line);border-radius:12px;padding:18px}
.control-row{margin-bottom:14px}.control-row:last-child{margin-bottom:0}
label{display:flex;justify-content:space-between;gap:10px;margin:8px 0;color:#d8e7f3}
input[type=range],select{width:100%}
select,input[type=text]{padding:10px;border:1px solid #31536f;border-radius:9px;background:#030a12;color:#fff}
.metric-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:12px;margin-top:14px}
.metric{background:var(--panel2);border:1px solid var(--line);border-radius:12px;padding:14px}
.metric small{display:block;color:var(--muted)}.metric strong{font-size:22px;color:var(--cyan)}
.bar{height:11px;border-radius:999px;background:#07111f;border:1px solid var(--line);overflow:hidden;margin-top:6px}
.fill{height:100%;background:linear-gradient(90deg,var(--cyan),var(--violet));width:0;transition:.35s}
.tools{display:flex;gap:9px;flex-wrap:wrap;margin-top:11px}
button,.download{min-height:40px;padding:0 13px;border:1px solid #3c5f7d;border-radius:8px;background:#15314a;color:#fff;font-weight:800;cursor:pointer;display:inline-flex;align-items:center;justify-content:center}
.primary{background:#0e7490;border-color:#22b8d6}
.quiz-question{padding:18px;border:1px solid var(--line);border-radius:12px;background:var(--panel2);margin-bottom:14px}
.quiz-option{display:block;padding:9px 11px;margin:7px 0;border:1px solid var(--line);border-radius:8px;cursor:pointer}
.quiz-option:hover{background:#153956}.quiz-result{margin-top:16px;padding:14px;border-radius:10px;background:#07111f;border:1px solid var(--line);font-weight:800}
.correct{border-color:#2d6f59;background:#0d3027}.incorrect{border-color:#7f3b45;background:#361b22}
.download-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:12px}
.nav{display:flex;justify-content:space-between;gap:12px;flex-wrap:wrap}
.site-footer{border-top:1px solid var(--line);background:#06111d;margin-top:30px}
.footer-grid{display:grid;grid-template-columns:1.5fr 1fr 1fr;gap:24px;padding:34px 0}
.footer-grid h3{margin:0 0 8px}.footer-grid p,.footer-grid a{color:var(--muted);font-size:13px}.footer-grid a{display:block;margin:5px 0}
.copyright{text-align:center;padding:16px;border-top:1px solid var(--line);color:var(--muted);font-size:12px}
@media(max-width:900px){.layout{grid-template-columns:1fr}.sidebar{position:static}.grid,.grid3,.metric-grid,.footer-grid{grid-template-columns:1fr 1fr}.header-links{display:none}}
@media(max-width:620px){.download-grid,.grid,.grid3,.metric-grid,.footer-grid{grid-template-columns:1fr}.nav{flex-direction:column}.header-action{display:none}}