:root{
  --blue:#0d6efd;--navy:#0b1f3a;--cyan:#14b8d4;--mint:#18c99a;
  --yellow:#ffc72c;--bg:#f5f8fd;--card:#fff;--line:#dce7f4;
  --text:#13243a;--muted:#6c7c91;--danger:#b42335;
  --shadow:0 14px 40px rgba(17,50,91,.10)
}
*{box-sizing:border-box}
body{margin:0;font-family:Inter,Segoe UI,Arial,sans-serif;background:linear-gradient(135deg,#f3f9ff,#fffdf6);color:var(--text)}
a{color:inherit;text-decoration:none}
.topbar{height:72px;display:flex;align-items:center;justify-content:space-between;padding:0 max(22px,4vw);background:#fff;border-bottom:1px solid var(--line);position:sticky;top:0;z-index:5}
.brand{display:flex;align-items:center;gap:10px;font-weight:900;font-size:24px;color:var(--navy)}
.brand>span:last-child>span{color:var(--blue)}
.brandmark{display:grid;place-items:center;width:38px;height:38px;border-radius:12px;background:linear-gradient(135deg,var(--cyan),var(--blue));color:#fff}
nav{display:flex;gap:16px;align-items:center}.teacher{color:var(--muted);font-weight:700}.logout{color:var(--danger);font-weight:800}
.shell{width:min(1180px,94vw);margin:34px auto 70px}
.hero{background:linear-gradient(125deg,#0b56d8,#16b8ca);color:#fff;border-radius:28px;padding:34px;box-shadow:var(--shadow)}
.hero h1{margin:0 0 8px;font-size:clamp(30px,5vw,48px)}.hero p{margin:0;opacity:.92;font-size:17px}.hero-gap{margin-top:16px}
.grid{display:grid;grid-template-columns:repeat(4,1fr);gap:16px;margin-top:18px}
.card{background:var(--card);border:1px solid var(--line);border-radius:20px;padding:20px;box-shadow:var(--shadow)}
.metric b{display:block;font-size:30px;color:var(--blue)}.metric span{color:var(--muted)}
.banner{margin:20px 0;padding:20px 22px;border:1px solid #ffd66d;background:#fff8dc;border-radius:20px;display:flex;justify-content:space-between;gap:18px;align-items:center}
.banner strong{font-size:19px}.banner p{margin:5px 0 0;color:#695a27}
.btn{display:inline-flex;align-items:center;justify-content:center;padding:12px 17px;border:0;border-radius:13px;background:var(--blue);color:#fff;font-weight:850;cursor:pointer}
.btn.alt{background:#eef5ff;color:#0d55c7;border:1px solid #cfe0fb}.btn.green{background:#0faf73}.btn.danger{background:#fff0f1;color:#a92132}
.panel{margin-top:20px;background:#fff;border:1px solid var(--line);border-radius:22px;padding:22px;box-shadow:var(--shadow)}
.panel h2{margin:0 0 18px}.row{display:flex;gap:12px;flex-wrap:wrap}.field{flex:1;min-width:180px}
label{display:block;font-weight:800;margin:0 0 7px}input,select,textarea{width:100%;padding:12px 13px;border:1px solid #cbd8e8;border-radius:12px;font:inherit;background:#fff}textarea{min-height:130px}
table{width:100%;border-collapse:collapse}th,td{padding:11px;border-bottom:1px solid #e7eef7;text-align:left}th{font-size:13px;color:#62748b}.grade{width:82px}.pass{color:#087b55;font-weight:900}.fail{color:#b42335;font-weight:900}
.alert{padding:13px 15px;border-radius:13px;margin:12px 0}.alert.error{background:#fff0f1;color:#9d2030}.alert.ok{background:#eafaf4;color:#087555}
.loginwrap{min-height:calc(100vh - 150px);display:grid;place-items:center}.loginbox{width:min(880px,96vw);display:grid;grid-template-columns:1fr 1fr;background:#fff;border:1px solid var(--line);border-radius:28px;overflow:hidden;box-shadow:0 30px 80px rgba(17,50,91,.15)}
.loginintro{padding:46px;background:linear-gradient(145deg,#075adf,#14b7cc);color:#fff}.loginintro h1{font-size:44px;margin:15px 0 10px}.loginintro p{line-height:1.55;opacity:.95}.loginform{padding:44px}.tabs{display:flex;gap:10px;margin-bottom:22px}.tabs a{padding:10px 14px;border-radius:999px;background:#eef5ff;color:#0d55c7;font-weight:850}.tabs a.active{background:var(--blue);color:#fff}
footer{text-align:center;color:var(--muted);padding:25px}
@media(max-width:850px){.grid{grid-template-columns:1fr 1fr}.loginbox{grid-template-columns:1fr}.loginintro{padding:30px}.loginform{padding:30px}}
@media(max-width:580px){.grid{grid-template-columns:1fr}.banner{align-items:flex-start;flex-direction:column}.teacher{display:none}.shell{width:94vw;margin-top:20px}table{font-size:14px}.panel{overflow-x:auto}}