:root{
  --bg:#eef3f9;--surface:#fff;--surface-2:#f8fafc;--text:#0f172a;--muted:#64748b;--line:#dfe7ef;
  --primary:#2563eb;--primary-dark:#1e3a8a;--success:#16a34a;--danger:#dc2626;--warning:#f59e0b;--violet:#7c3aed;
  --shadow:0 10px 30px rgba(15,23,42,.06);--radius:16px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",Arial,sans-serif;background:var(--bg);color:var(--text)}
a{color:inherit}
button,input,select,textarea{font:inherit}
button{cursor:pointer}
.container{max-width:1200px;margin:auto;padding:22px}
.icon{display:inline-block;vertical-align:middle;flex:0 0 auto}
.muted{color:var(--muted)}
.small-text{font-size:12px;color:var(--muted)}
.hidden{display:none!important}
.row{display:flex;align-items:center;justify-content:space-between;gap:14px;flex-wrap:wrap}
.stack{display:grid;gap:12px}
.grid-2{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:14px}
.grid-3{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px}
.grid-4{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:12px}
.panel,.card,.auth-card{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);box-shadow:var(--shadow)}
.panel{padding:22px}
.card{padding:18px}
.auth-card{width:min(460px,94vw);padding:28px;margin:60px auto}
.section-title{margin:0 0 14px;font-size:20px}
.input-group{margin-bottom:14px}
.input-group label{display:block;font-size:13px;font-weight:800;color:#475569;margin-bottom:6px}
.input-group input,.input-group select,.input-group textarea{width:100%;border:1px solid #cbd5e1;border-radius:10px;padding:11px 12px;background:#fff;outline:none}
.input-group input:focus,.input-group select:focus,.input-group textarea:focus{border-color:var(--primary);box-shadow:0 0 0 3px rgba(37,99,235,.12)}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:7px;border:0;border-radius:10px;padding:10px 14px;font-weight:800;text-decoration:none;transition:.18s ease}
.btn:hover{transform:translateY(-1px)}
.btn-primary{background:var(--primary);color:#fff}.btn-success{background:var(--success);color:#fff}.btn-danger{background:var(--danger);color:#fff}.btn-warning{background:var(--warning);color:#fff}.btn-violet{background:var(--violet);color:#fff}.btn-dark{background:#0f172a;color:#fff}.btn-light{background:#f1f5f9;color:#334155;border:1px solid #e2e8f0}
.btn-sm{padding:7px 10px;font-size:12px;border-radius:8px}
.badge{display:inline-flex;align-items:center;border-radius:999px;padding:5px 9px;font-size:11px;font-weight:900}.badge-success{background:#dcfce7;color:#166534}.badge-warning{background:#fef3c7;color:#92400e}.badge-danger{background:#fee2e2;color:#991b1b}.badge-blue{background:#dbeafe;color:#1d4ed8}.badge-violet{background:#ede9fe;color:#5b21b6}.badge-gray{background:#e2e8f0;color:#475569}
.notice{background:#eff6ff;border-left:4px solid var(--primary);padding:12px 14px;border-radius:8px;color:#1e3a8a;font-size:13px}
.stat-card{padding:18px;border:1px solid var(--line);background:linear-gradient(180deg,#fff,#f8fafc);border-radius:14px}
.stat-card .label{font-size:13px;color:var(--muted)}.stat-card strong{display:block;font-size:30px;margin-top:5px}
.site-header{position:sticky;top:0;z-index:30;background:rgba(30,58,138,.96);backdrop-filter:blur(10px);color:#fff;padding:14px 20px}
.site-header .inner{max-width:1200px;margin:auto;display:flex;align-items:center;justify-content:space-between;gap:16px}
.brand{font-weight:900;font-size:20px;text-decoration:none}.site-nav{display:flex;gap:8px;flex-wrap:wrap}.site-nav a{background:rgba(255,255,255,.12);padding:9px 12px;border-radius:9px;text-decoration:none;font-weight:800}
.hero{padding:78px 20px;color:#fff;background:linear-gradient(135deg,var(--primary-dark),var(--primary));text-align:center}.hero h1{font-size:clamp(36px,6vw,58px);margin:0 0 15px}.hero p{max-width:760px;margin:0 auto 28px;font-size:18px;line-height:1.6;opacity:.94}
.hero-btn{display:inline-flex;align-items:center;gap:8px;background:var(--warning);color:#fff;padding:13px 20px;border-radius:11px;font-weight:900;text-decoration:none}
.feature-card h3{margin:0 0 7px}.feature-card p{margin:0;color:var(--muted);line-height:1.55}
.footer{background:#0f172a;color:#94a3b8;padding:28px;text-align:center}
.student-shell{max-width:1150px;margin:auto;padding:18px}.student-top{background:linear-gradient(135deg,#1e3a8a,#2563eb);color:#fff;border-radius:20px;padding:22px;box-shadow:0 12px 35px rgba(37,99,235,.18)}.student-top h1{font-size:24px;margin:0 0 4px}.student-top p{margin:0;opacity:.9}.student-actions{display:flex;gap:8px;flex-wrap:wrap;margin-top:14px}.student-actions a,.student-actions button{border:0;padding:9px 12px;border-radius:9px;font-weight:800;text-decoration:none}.student-actions a{background:rgba(255,255,255,.14);color:#fff}.student-actions button{background:#fff;color:#1e3a8a}
.quick-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px;margin:16px 0}.quick-card{background:#fff;border:1px solid var(--line);padding:16px;border-radius:14px}.quick-card span{display:block;color:var(--muted);font-size:12px}.quick-card strong{display:block;font-size:26px;margin-top:4px}
.list{display:grid;gap:12px}.list-item{background:#fff;border:1px solid var(--line);border-radius:14px;padding:17px}.list-item .title{font-size:16px;font-weight:900}.list-item .meta{font-size:12px;color:var(--muted);margin-top:4px;line-height:1.55}.list-item .price{font-size:19px;font-weight:900;color:var(--warning)}.list-item .price.free{color:var(--success)}
.admin-shell{max-width:1280px;margin:auto;padding:20px}.admin-top{display:flex;align-items:center;justify-content:space-between;gap:16px;margin-bottom:15px}.admin-top h1{margin:0;font-size:25px}.admin-tabs{display:grid;grid-template-columns:repeat(auto-fit,minmax(145px,1fr));gap:9px;margin-bottom:16px}.admin-tab{display:flex;align-items:center;gap:8px;border:1px solid var(--line);background:#fff;color:#334155;padding:11px 12px;border-radius:12px;font-weight:850}.admin-tab.active{background:#0f172a;color:#fff;border-color:#0f172a}.admin-tab:hover{border-color:#94a3b8}.admin-content{display:none}.admin-content.active{display:block}.admin-panel{background:#fff;border:1px solid var(--line);border-radius:16px;box-shadow:var(--shadow);padding:20px;margin-bottom:16px}.admin-panel h2{margin:0 0 14px;font-size:20px}.toolbar{display:flex;gap:8px;flex-wrap:wrap;align-items:center}.table-wrap{overflow:auto;border:1px solid var(--line);border-radius:12px}.table{width:100%;border-collapse:collapse;min-width:720px}.table th,.table td{padding:11px 12px;border-bottom:1px solid var(--line);text-align:left;font-size:13px}.table th{background:#f8fafc;color:#475569}.table tr:last-child td{border-bottom:0}.switch{position:relative;width:48px;height:28px;display:inline-block}.switch input{opacity:0;width:0;height:0}.slider{position:absolute;inset:0;border-radius:30px;background:#cbd5e1;transition:.2s}.slider:before{content:"";position:absolute;width:22px;height:22px;left:3px;top:3px;background:#fff;border-radius:50%;transition:.2s;box-shadow:0 1px 3px rgba(0,0,0,.18)}.switch input:checked+.slider{background:var(--success)}.switch input:checked+.slider:before{transform:translateX(20px)}
.exam-terminal{height:100dvh;display:flex;flex-direction:column;overflow:hidden;background:#fff}.exam-header{background:#1e3a8a;color:#fff;padding:10px 14px;display:flex;align-items:center;justify-content:space-between;gap:12px}.exam-header h2{margin:0;font-size:16px}.timer{background:#dc2626;color:#fff;padding:6px 13px;border-radius:7px;font:900 18px/1 monospace}.exam-body{flex:1;display:flex;min-height:0}.exam-main{flex:1;overflow:auto;padding:18px}.exam-side{width:260px;border-left:1px solid #cbd5e1;background:#f8fafc;padding:12px;overflow:auto}.question-head{display:flex;justify-content:space-between;gap:10px;color:#475569;font-weight:850;border-bottom:1px solid #e2e8f0;padding-bottom:10px}.question-text{font-size:18px;line-height:1.6;margin:18px 0}.question-image{display:block;max-width:100%;max-height:280px;margin:10px auto;border:1px solid #ddd;border-radius:8px}.option{display:block;padding:14px;margin:10px 0;border:1px solid #cbd5e1;border-radius:10px;background:#f8fafc}.option.selected{background:#dbeafe;border-color:#2563eb}.exam-footer{background:#f1f5f9;border-top:1px solid #cbd5e1;padding:10px;display:flex;gap:8px;flex-wrap:wrap}.exam-footer button{flex:1;border:0;padding:10px;border-radius:8px;color:#fff;font-weight:850}.palette{display:grid;grid-template-columns:repeat(5,1fr);gap:6px}.palette button{padding:9px 0;border:1px solid #cbd5e1;background:#fff;border-radius:5px;font-weight:850}.palette .answered{background:#16a34a;color:#fff}.palette .marked{background:#7c3aed;color:#fff}.palette .notans{background:#dc2626;color:#fff}.palette .current{outline:3px solid #2563eb}.modal{display:none;position:fixed;inset:0;background:rgba(0,0,0,.62);align-items:center;justify-content:center;z-index:100;padding:15px}.modal-box{background:#fff;padding:24px;border-radius:14px;width:min(450px,94vw)}.result-view,.review-view{display:none;max-width:850px;margin:auto;padding:24px}.score{font-size:48px;font-weight:950;text-align:center;color:var(--success)}
@media(max-width:900px){.admin-tabs{grid-template-columns:repeat(2,minmax(0,1fr))}.grid-4{grid-template-columns:repeat(2,minmax(0,1fr))}.exam-side{width:230px}}
@media(max-width:760px){.container,.admin-shell,.student-shell{padding:12px}.grid-2,.grid-3,.grid-4,.quick-grid{grid-template-columns:1fr}.admin-tabs{grid-template-columns:repeat(2,minmax(0,1fr))}.admin-top{align-items:flex-start;flex-direction:column}.exam-body{flex-direction:column}.exam-side{width:100%;height:175px;border-left:0;border-top:1px solid #cbd5e1}.palette{grid-template-columns:repeat(8,1fr)}.exam-footer button{font-size:12px}.hero{padding:62px 16px}}