:root{
  --navy:#0b1f5c; --navy2:#13307f; --ink:#14213d; --muted:#5b6782; --line:#dfe5f1; --bg:#f5f7fc; --card:#fff;
  --accent:#e5469b; --violet:#7b5cff; --green:#18a058; --amber:#e8a317; --red:#d64045; --teal:#0f9fb5;
  --radius:16px; --shadow:0 10px 30px rgba(11,31,92,.08);
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;font-family:"Be Vietnam Pro",system-ui,-apple-system,Segoe UI,Roboto,sans-serif;color:var(--ink);background:var(--bg);line-height:1.55;font-size:16px}
a{color:var(--navy2)}
.wrap{max-width:1140px;margin:0 auto;padding:0 20px}
.wrap.wide{max-width:1320px}.wrap.narrow{max-width:760px}
.muted{color:var(--muted)}.small{font-size:.88rem}.center{text-align:center}.mt{margin-top:24px}.w100{width:100%}
/* topbar */
.topbar{background:#fff;border-bottom:1px solid var(--line);position:sticky;top:0;z-index:20}
.topbar-in{display:flex;align-items:center;justify-content:space-between;gap:16px;min-height:64px;flex-wrap:wrap}
.brand{display:flex;gap:10px;align-items:center;text-decoration:none;color:var(--ink)}
.brand .logo{width:40px;height:40px;border-radius:12px;background:linear-gradient(135deg,var(--navy),var(--violet));color:#fff;display:grid;place-items:center;font-size:22px}
.brand b{display:block;font-size:.98rem}.brand small{color:var(--muted);font-size:.78rem}
.nav{display:flex;gap:14px;align-items:center;flex-wrap:wrap}
.nav a{text-decoration:none;color:var(--ink);font-weight:500;font-size:.92rem}
.nav .who{color:var(--muted);font-size:.88rem}
.btn-sm{display:inline-block;padding:6px 12px;border-radius:999px;border:1px solid var(--line);background:#fff;font-size:.85rem;font-weight:600;cursor:pointer;color:var(--navy2);text-decoration:none;font-family:inherit}
.btn-sm:hover{border-color:var(--navy2)}.btn-sm.warn{color:#9a6200}.btn-sm.danger{color:var(--red)}
.btn{display:inline-block;padding:12px 22px;border-radius:12px;border:0;background:var(--navy2);color:#fff;font-weight:700;font-size:1rem;cursor:pointer;text-decoration:none;font-family:inherit}
.btn:hover{filter:brightness(1.1)}.btn:disabled{opacity:.6;cursor:wait}
.btn-go{background:linear-gradient(135deg,var(--accent),var(--violet))}
.btn.ghost{background:#fff;color:var(--navy2);border:1px solid var(--line)}
.btn.big{padding:16px 40px;font-size:1.1rem}
/* hero */
.hero{background:radial-gradient(1200px 500px at 85% -10%,rgba(123,92,255,.45),transparent 60%),radial-gradient(800px 400px at 0% 110%,rgba(229,70,155,.35),transparent 60%),linear-gradient(160deg,#071544,var(--navy) 55%,#16267a);color:#fff;padding:64px 0 72px}
.hero-grid{display:grid;grid-template-columns:1.25fr .9fr;gap:40px;align-items:center}
.eyebrow{display:inline-block;font-size:.8rem;letter-spacing:.06em;text-transform:uppercase;font-weight:600;color:#f6b6dc;background:rgba(255,255,255,.08);padding:6px 12px;border-radius:999px}
.hero h1{font-size:clamp(2rem,4.2vw,3.1rem);line-height:1.15;margin:18px 0 12px;font-weight:800}
.hero h1 em{font-style:normal;background:linear-gradient(90deg,#ffd1ea,#c9bbff);-webkit-background-clip:text;background-clip:text;color:transparent}
.lead{color:#cdd6f6;margin:0 0 22px}
.teachers{display:flex;gap:12px;flex-wrap:wrap;margin-bottom:26px}
.t-card{display:flex;gap:10px;align-items:center;background:rgba(255,255,255,.09);border:1px solid rgba(255,255,255,.16);padding:10px 16px 10px 10px;border-radius:14px}
.t-card .av{width:40px;height:40px;border-radius:50%;background:linear-gradient(135deg,var(--accent),var(--violet));display:grid;place-items:center;font-weight:700;font-size:.85rem}
.t-card small{display:block;color:#c3cbe8;font-size:.74rem}
.stats{display:grid;grid-template-columns:repeat(4,1fr);gap:12px;max-width:560px}
.stats div{background:rgba(255,255,255,.07);border-radius:14px;padding:12px;text-align:center}
.stats b{display:block;font-size:1.7rem;font-weight:800}.stats span{font-size:.78rem;color:#c3cbe8}
.hero-card{background:#fff;color:var(--ink);border-radius:22px;padding:28px;box-shadow:0 30px 60px rgba(0,0,0,.25)}
.hero-card h2{margin:0 0 6px;font-size:1.35rem}
.form label,form label{display:block;font-weight:600;font-size:.9rem;margin:12px 0}
input[type=text],input:not([type]),input[type=password],input[type=number],textarea{width:100%;margin-top:6px;padding:12px 14px;border:1.5px solid var(--line);border-radius:12px;font:inherit;font-weight:400;background:#fbfcff}
input:focus,textarea:focus{outline:none;border-color:var(--violet);box-shadow:0 0 0 4px rgba(123,92,255,.12)}
.form .btn{width:100%;margin-top:8px}
label.check{display:flex;gap:10px;align-items:flex-start;font-weight:500}
label.check input{margin-top:4px;width:18px;height:18px}
.info{display:grid;grid-template-columns:auto 1fr;gap:6px 16px;background:var(--bg);padding:14px 16px;border-radius:12px;margin:14px 0}
.info dt{color:var(--muted)}.info dd{margin:0;font-weight:600}
#startForm .btn{width:100%}
/* sections */
.sec{padding:56px 0}.sec.alt{background:#fff;border-top:1px solid var(--line);border-bottom:1px solid var(--line)}
.sec-title{font-size:1.6rem;margin:0 0 26px;display:flex;align-items:center;gap:12px}
.sec-title span{font-size:.85rem;background:var(--navy);color:#fff;border-radius:10px;padding:4px 10px}
.cards{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:22px;box-shadow:var(--shadow)}
.card h3{margin:8px 0 6px;font-size:1.08rem}.card p{margin:0;color:#3c4766;font-size:.95rem}
.card .ic{font-size:1.6rem;width:48px;height:48px;border-radius:14px;background:var(--bg);display:grid;place-items:center}
.note{background:#fff7e6;border:1px solid #f7deaa;border-radius:12px;padding:14px 16px;margin:20px 0;font-size:.95rem}
.two{display:grid;grid-template-columns:1.1fr 1fr;gap:24px;align-items:start}
.tbl{width:100%;border-collapse:collapse;background:#fff;border-radius:14px;overflow:hidden;border:1px solid var(--line)}
.tbl th{background:var(--navy);color:#fff;text-align:left;padding:10px 12px;font-size:.88rem;font-weight:600}
.tbl td{padding:10px 12px;border-top:1px solid var(--line);font-size:.93rem;vertical-align:middle}
.tbl tr.sum td{font-weight:700;background:var(--bg)}
.tbl-wrap{overflow-x:auto;border-radius:14px}
.essay-box{background:linear-gradient(160deg,#f3efff,#fff);border:1px solid #e1d9ff;border-radius:var(--radius);padding:22px}
.essay-box h3{margin-top:0}.essay-box li{margin-bottom:10px}
.topics{display:grid;grid-template-columns:repeat(auto-fill,minmax(250px,1fr));gap:14px}
.topics div{background:#fff;border:1px solid var(--line);border-left:4px solid var(--violet);border-radius:12px;padding:14px 16px}
.topics b{display:block}.topics span{color:var(--muted);font-size:.9rem}
.foot{background:#071544;color:#aeb8dc;padding:26px 0;font-size:.88rem}.foot .wrap{display:flex;justify-content:space-between;gap:12px;flex-wrap:wrap}
.flash{padding:12px 14px;border-radius:12px;margin:12px 0;font-weight:500}
.flash.ok{background:#e7f7ee;color:#11653a}.flash.err{background:#fde8e9;color:#a1232a}.flash.warn{background:#fff4dc;color:#8a5a00}
/* exam */
.exam-bar{position:sticky;top:64px;z-index:15;background:var(--navy);color:#fff}
.exam-bar-in{display:flex;justify-content:space-between;align-items:center;gap:12px;min-height:58px;flex-wrap:wrap;font-size:.92rem}
.timer{font-variant-numeric:tabular-nums;font-size:1.7rem;font-weight:800;background:rgba(255,255,255,.12);padding:4px 16px;border-radius:12px;letter-spacing:.04em}
.timer.warn{background:var(--amber);color:#2b1d00}.timer.crit{background:var(--red);color:#fff;animation:pulse 1s infinite}
@keyframes pulse{50%{opacity:.7}}
.save{padding:2px 8px;border-radius:8px;font-size:.8rem}.save.ok{background:rgba(24,160,88,.25)}.save.pending{background:rgba(232,163,23,.3)}.save.err{background:var(--red)}
.exam-layout{display:grid;grid-template-columns:250px 1fr;gap:24px;padding-top:24px;padding-bottom:40px}
.navgrid{position:sticky;top:140px;align-self:start;background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:16px;max-height:calc(100vh - 160px);overflow:auto}
.navgrid h4{margin:0 0 10px}
.navgrid .grid{display:grid;grid-template-columns:repeat(6,1fr);gap:5px;margin-bottom:14px}
.navgrid .grid a{display:grid;place-items:center;height:30px;border-radius:7px;background:var(--bg);font-size:.78rem;text-decoration:none;color:var(--ink);border:1px solid var(--line)}
.navgrid .grid a.done{background:var(--navy2);color:#fff;border-color:var(--navy2)}
.navgrid .grid a.tl{grid-column:span 3}
.part{font-size:1.1rem;background:#eef1fb;padding:10px 14px;border-radius:12px;margin:26px 0 14px}
.q{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:18px 20px;margin-bottom:14px;scroll-margin-top:140px}
.q.small{padding:12px 16px}
.qh{font-weight:500;margin-bottom:12px}
.qn{display:inline-block;background:var(--navy);color:#fff;border-radius:8px;padding:1px 9px;font-size:.85rem;margin-right:6px;font-weight:700}
.opts{display:grid;gap:8px}
.opt{display:flex;gap:12px;align-items:flex-start;padding:10px 12px;border:1.5px solid var(--line);border-radius:12px;cursor:pointer;font-weight:400;margin:0}
.opt:hover{border-color:#b9b0ff;background:#faf9ff}
.opt input{position:absolute;opacity:0;pointer-events:none}
.opt .L{flex:0 0 28px;height:28px;border-radius:50%;border:1.5px solid var(--line);display:grid;place-items:center;font-weight:700;font-size:.85rem}
.opt.sel{border-color:var(--violet);background:#f3f0ff}.opt.sel .L{background:var(--violet);color:#fff;border-color:var(--violet)}
.q textarea{min-height:220px;font-size:1rem;line-height:1.6}
.wc{text-align:right;color:var(--muted);font-size:.82rem;margin-top:4px}
.modal{position:fixed;inset:0;background:rgba(7,21,68,.55);display:grid;place-items:center;z-index:50;padding:16px}
.modal[hidden]{display:none}
.modal-box{background:#fff;border-radius:20px;padding:26px;max-width:460px;width:100%}
.modal-box h3{margin-top:0}
.row{display:flex;gap:10px;justify-content:flex-end;flex-wrap:wrap;margin-top:16px}
.toast{position:fixed;bottom:22px;left:50%;transform:translateX(-50%);background:var(--ink);color:#fff;padding:12px 20px;border-radius:12px;z-index:60;box-shadow:var(--shadow)}
.toast[hidden]{display:none}
/* result */
.result-card{background:#fff;border:1px solid var(--line);border-radius:22px;padding:32px;box-shadow:var(--shadow);text-align:center}
.result-card .eyebrow{background:#eef1fb;color:var(--navy2)}
.result-card h1{margin:14px 0 4px}
.score-row{display:grid;grid-template-columns:1.3fr 1fr 1fr;gap:14px;margin:24px 0}
.score{background:var(--bg);border-radius:16px;padding:18px}
.score small{display:block;color:var(--muted)}.score b{display:block;font-size:2rem;font-weight:800;color:var(--navy)}.score span{color:var(--muted);font-size:.85rem}
.score.big{background:linear-gradient(135deg,var(--navy),var(--violet));color:#fff}.score.big b{color:#fff;font-size:2.8rem}.score.big small,.score.big span{color:#d8dcff}
.score b.pending{font-size:1.2rem;color:var(--amber);padding:12px 0}
.total{font-size:1.3rem;margin:10px 0}
/* admin */
.head-row{display:flex;justify-content:space-between;align-items:center;gap:12px;flex-wrap:wrap;margin-bottom:16px}
.head-row h1{margin:6px 0}
.kpis{display:grid;grid-template-columns:repeat(auto-fit,minmax(160px,1fr));gap:12px;margin-bottom:18px}
.kpis div{background:#fff;border:1px solid var(--line);border-radius:14px;padding:14px 16px}
.kpis b{display:block;font-size:1.6rem;color:var(--navy)}.kpis span{color:var(--muted);font-size:.85rem}
.tbl.grade td{white-space:nowrap}.tbl td.name{white-space:nowrap;font-weight:600}
.tot{color:var(--accent);font-size:1.05rem}
.tag{display:inline-block;padding:2px 9px;border-radius:999px;font-size:.78rem;font-weight:600}
.tag.gray{background:#eef0f5;color:#6b7590}.tag.amber{background:#fff1d4;color:#8a5a00}.tag.green{background:#e3f6ec;color:#11653a}
.acts{display:flex;gap:6px;flex-wrap:wrap}.acts form{display:inline-flex;gap:4px;margin:0}
input.mini{width:60px;margin:0;padding:4px 6px}
.essay-ans{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:20px;margin-bottom:16px}
.essay-ans h3{margin:0 0 4px}
.ans-text{background:var(--bg);border-radius:12px;padding:14px 16px;white-space:normal;line-height:1.7;max-height:480px;overflow:auto}
.score-in input{width:120px;display:inline-block;margin-left:8px}
.codes{display:grid;grid-template-columns:repeat(auto-fill,minmax(150px,1fr));gap:10px}
.code{background:#fff;border:1px solid var(--line);border-radius:12px;padding:10px 12px;text-decoration:none;color:var(--ink)}
.code b{display:block;font-size:1.1rem}.code small{color:var(--muted);font-size:.75rem;display:block;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.code.used{border-color:#b9b0ff;background:#f6f4ff}
.anskey{display:grid;grid-template-columns:repeat(10,1fr);gap:4px;background:#fff;border:1px solid var(--line);border-radius:12px;padding:12px;margin-bottom:16px;font-size:.85rem}
.opt-view{padding:3px 8px;border-radius:6px}.opt-view.right{background:#e3f6ec;font-weight:600}
@media (max-width:900px){
  .hero-grid,.two{grid-template-columns:1fr}.cards{grid-template-columns:1fr 1fr}
  .exam-layout{grid-template-columns:1fr}.navgrid{position:static;max-height:none}
  .navgrid .grid{grid-template-columns:repeat(10,1fr)}
}
@media (max-width:600px){
  .cards{grid-template-columns:1fr}.stats{grid-template-columns:repeat(2,1fr)}
  .score-row{grid-template-columns:1fr}.wrap{padding:0 16px}.hero{padding:40px 0}
  .exam-bar{top:0}.topbar{position:static}.timer{font-size:1.4rem}
  .anskey{grid-template-columns:repeat(5,1fr)}
}
@media print{.topbar,.foot,.btn{display:none}.q{break-inside:avoid;border:0;padding:4px 0}}