:root{--bg:#F3F5F8;--surface:#fff;--ink:#16212B;--muted:#6B7684;--line:#D9DEE5;--attn:#D9891C;--ok:#2C7A5B;--bad:#B3362B;--radius:10px}
*{box-sizing:border-box}html,body{margin:0;background:var(--bg);color:var(--ink);font-family:system-ui,-apple-system,"Segoe UI",Roboto,"Helvetica Neue",sans-serif;font-size:16px;line-height:1.55}
button{font:inherit;cursor:pointer}a{color:var(--primary)}
button:focus-visible,input:focus-visible,select:focus-visible,a:focus-visible{outline:3px solid var(--attn);outline-offset:2px}
.app{max-width:720px;margin:0 auto;min-height:100vh;display:flex;flex-direction:column}
.top{position:sticky;top:0;z-index:5;background:var(--surface);border-bottom:1px solid var(--line);padding:10px 16px}
.top-row{display:flex;align-items:center;justify-content:space-between;gap:12px}
.brand{display:flex;align-items:center;gap:10px;text-decoration:none;color:var(--ink)}.brand .logo{height:32px;max-width:160px;object-fit:contain}
.brandtext{font-weight:700;color:var(--primary)}.brand .sub{font-size:13px;color:var(--muted)}
.nav{display:flex;gap:14px;margin-top:8px;font-size:14px;flex-wrap:wrap}.nav a{text-decoration:none}.nav .right{margin-left:auto}
.attn{display:flex;align-items:center;gap:8px;font-size:13px;color:var(--muted)}
.ring{width:30px;height:30px;border-radius:50%;background:conic-gradient(var(--attn) var(--p,0%),var(--line) 0);display:grid;place-items:center}
.ring::after{content:"";width:22px;height:22px;border-radius:50%;background:var(--surface)}.ring.paused{background:var(--ok)}
.rail{display:flex;gap:3px;margin-top:10px}.rail span{flex:1;height:5px;border-radius:3px;background:var(--line)}.rail span.done{background:var(--primary)}.rail span.now{background:var(--attn)}
main{padding:20px 16px 40px;flex:1}h1{font-size:26px;line-height:1.2;margin:0 0 6px}h2{font-size:20px;margin:0 0 10px}p{margin:0 0 14px;max-width:62ch}
.kicker{color:var(--muted);font-size:14px;margin-bottom:4px}
.card{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:18px;margin-bottom:14px}
.card.track{display:flex;justify-content:space-between;align-items:center;gap:12px;flex-wrap:wrap}.meta{color:var(--muted);font-size:14px}
.btn{display:inline-block;background:var(--primary);color:#fff;border:none;border-radius:8px;padding:12px 18px;font-weight:600;min-height:44px;text-decoration:none}
.btn:disabled{background:var(--line);color:var(--muted);cursor:not-allowed}.btn.ghost{background:var(--surface);color:var(--primary);border:1px solid var(--primary)}
.actions{display:flex;gap:10px;flex-wrap:wrap;align-items:center;margin-top:18px}.hint{font-size:14px;color:var(--muted)}
label{display:block;font-size:14px;font-weight:500;margin:12px 0 6px}input,select{width:100%;padding:11px 12px;border:1px solid var(--line);border-radius:8px;font:inherit;background:var(--surface)}
.tag{display:inline-block;font-size:12px;padding:3px 8px;border-radius:999px;background:var(--bg);border:1px solid var(--line);color:var(--muted)}.tag.ok{color:var(--ok);border-color:var(--ok)}.tag.bad{color:var(--bad);border-color:var(--bad)}.tag.warn{color:var(--attn);border-color:var(--attn)}
.story{border-left:4px solid var(--attn);padding-left:14px}.story dt{font-weight:600;margin-top:10px}.story dd{margin:2px 0 0}
.video{background:#0E1B22;border-radius:var(--radius);aspect-ratio:16/9;position:relative;overflow:hidden}.video video{width:100%;height:100%}
.video .placeholder{color:#fff;display:grid;place-items:center;height:100%;text-align:center;padding:20px}
.opt{display:block;width:100%;text-align:left;background:var(--surface);border:1px solid var(--line);border-radius:8px;padding:12px 14px;margin-bottom:8px}
.opt.sel{border-color:var(--primary);box-shadow:inset 0 0 0 1px var(--primary)}.opt.right{border-color:var(--ok);background:#EEF6F2}.opt.wrong{border-color:var(--bad);background:#FBEFED}
.feedback{margin-top:12px;padding:12px 14px;border-radius:8px;background:var(--bg);font-size:15px}
.overlay{position:fixed;inset:0;background:rgba(22,33,43,.7);display:none;align-items:center;justify-content:center;z-index:20;padding:20px}.overlay.on{display:flex}
.modal{background:var(--surface);border-radius:12px;padding:24px;max-width:420px;width:100%}.modal h2{margin-top:0}
.msg{padding:10px 14px;border-radius:8px;margin-bottom:12px;background:#EEF6F2;border:1px solid var(--ok)}.msg.error{background:#FBEFED;border-color:var(--bad)}
.errorlist{color:var(--bad);margin:6px 0 0;padding-left:18px;font-size:14px}
.score{font-size:44px;font-weight:700;line-height:1}.cert{border:2px solid var(--primary);border-radius:12px;padding:24px;text-align:center;background:var(--surface)}
table{width:100%;border-collapse:collapse;font-size:14px;background:var(--surface)}th,td{padding:8px 10px;border-bottom:1px solid var(--line);text-align:left;vertical-align:top}th{color:var(--muted);font-weight:600}
.foot{padding:14px 16px;font-size:13px;color:var(--muted);border-top:1px solid var(--line)}
.exam-q h2{user-select:none}
@media (max-width:480px){main{padding:14px 12px}h1{font-size:22px}}