:root{--bg:#f4f7fa;--card:#fff;--text:#18232d;--muted:#687583;--brand:#0b4f6c;--brand2:#11708e;--ok:#14865a;--bad:#c23b2d;--line:#d9e1e7;--soft:#eaf2f5}
*{box-sizing:border-box}body{margin:0;font-family:Arial,Helvetica,sans-serif;background:var(--bg);color:var(--text)}button,input,select{font:inherit}a{color:var(--brand)}
header{background:#0a3549;color:white;padding:18px 22px;position:sticky;top:0;z-index:5}header .in{max-width:1250px;margin:auto;display:flex;justify-content:space-between;gap:14px;align-items:center}h1{margin:0;font-size:24px}header small{opacity:.8}
.shell{max-width:1250px;margin:20px auto;display:grid;grid-template-columns:245px 1fr;gap:18px;padding:0 14px}.side,.card{background:var(--card);border:1px solid var(--line);border-radius:15px;box-shadow:0 10px 28px rgba(20,40,55,.07)}.side{padding:12px;height:max-content;position:sticky;top:90px}
.nav{width:100%;text-align:left;border:0;background:transparent;padding:12px;border-radius:9px;cursor:pointer}.nav:hover,.nav.active{background:var(--soft);color:var(--brand);font-weight:bold}.page{display:none}.page.active{display:block}.card{padding:22px;margin-bottom:16px}h2,h3{color:var(--brand)}
.grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(190px,1fr));gap:12px}.metric{padding:15px;border:1px solid var(--line);border-radius:12px}.metric b{font-size:30px;display:block;color:var(--brand)}.progress{height:12px;background:#e5ebef;border-radius:999px;overflow:hidden}.progress i{display:block;height:100%;background:linear-gradient(90deg,var(--brand),#2a93b2);width:0}
.toolbar{display:flex;gap:8px;flex-wrap:wrap;align-items:center}.btn{border:0;border-radius:9px;padding:10px 13px;cursor:pointer;font-weight:bold}.primary{background:var(--brand);color:white}.secondary{background:#e8edf1}.danger{background:#fdeceb;color:var(--bad)}select,input{padding:10px;border:1px solid var(--line);border-radius:8px;background:white}
.tags{display:flex;gap:6px;flex-wrap:wrap}.tag{background:var(--soft);color:var(--brand);padding:5px 9px;border-radius:999px;font-size:12px;font-weight:bold}.q{font-size:20px;line-height:1.45}.option{display:block;width:100%;text-align:left;border:1px solid var(--line);background:white;padding:13px;border-radius:10px;margin:8px 0;cursor:pointer}.option.selected{outline:2px solid var(--brand2)}.option.correct{background:#e9f8f1;border-color:var(--ok);color:#0b6241}.option.wrong{background:#fff0ef;border-color:var(--bad);color:#8c2a20}
.feedback{display:none;padding:15px;margin-top:15px;border-radius:10px;border-left:5px solid}.feedback.show{display:block}.feedback.ok{background:#e9f8f1;border-color:var(--ok)}.feedback.bad{background:#fff0ef;border-color:var(--bad)}.tip,.note{padding:12px;border-radius:9px;margin-top:10px}.tip{background:#fff6df;border-left:4px solid #d79a27}.note{background:#eef3f6;border-left:4px solid #8ca0ac}
table{width:100%;border-collapse:collapse}th,td{padding:10px;border-bottom:1px solid var(--line);text-align:left}th{background:#eef3f6}details{border:1px solid var(--line);padding:11px;border-radius:9px;margin:8px 0}summary{cursor:pointer;font-weight:bold;color:var(--brand)}
.timer{font-size:20px;font-weight:bold;color:var(--brand)}footer{text-align:center;padding:25px;color:var(--muted)}
@media(max-width:800px){header{position:static}.shell{grid-template-columns:1fr}.side{position:static}.side nav{display:grid;grid-template-columns:1fr 1fr}.q{font-size:18px}}