/* ============================================================
   IT 802 Learning Portal — Design System
   Premium, 100% responsive (mobile-first)
   ============================================================ */
:root{
  --brand:#4f46e5; --brand-dark:#3730a3; --brand-light:#eef2ff;
  --accent:#06b6d4; --success:#16a34a; --danger:#dc2626; --warn:#f59e0b;
  --ink:#0f172a; --muted:#64748b; --line:#e2e8f0; --bg:#f1f5f9;
  --card:#ffffff; --radius:16px; --shadow:0 10px 30px rgba(2,6,23,.08);
  --shadow-sm:0 2px 8px rgba(2,6,23,.06);
}
*{box-sizing:border-box;margin:0;padding:0}
html{-webkit-text-size-adjust:100%}
body{
  font-family:'Segoe UI',system-ui,-apple-system,Roboto,Arial,sans-serif;
  background:var(--bg);color:var(--ink);line-height:1.55;
  -webkit-font-smoothing:antialiased;
}
a{color:var(--brand);text-decoration:none}
img{max-width:100%;display:block}

/* ---------- Layout ---------- */
.container{width:100%;max-width:1160px;margin:0 auto;padding:0 16px}
.row{display:flex;flex-wrap:wrap;gap:16px}
.col{flex:1 1 260px}
.grid{display:grid;gap:16px}
.grid-2{grid-template-columns:repeat(auto-fill,minmax(280px,1fr))}
.grid-3{grid-template-columns:repeat(auto-fill,minmax(230px,1fr))}
.grid-4{grid-template-columns:repeat(auto-fill,minmax(200px,1fr))}

/* ---------- Auth / Landing ---------- */
.auth-wrap{min-height:100vh;display:flex;align-items:center;justify-content:center;
  padding:24px;background:linear-gradient(135deg,var(--brand) 0%,var(--brand-dark) 50%,#1e1b4b 100%)}
.auth-card{background:var(--card);border-radius:22px;box-shadow:0 30px 60px rgba(0,0,0,.3);
  width:100%;max-width:920px;overflow:hidden;display:grid;grid-template-columns:1fr 1fr}
.auth-hero{background:linear-gradient(160deg,var(--brand-dark),#1e1b4b);color:#fff;padding:44px 36px;
  display:flex;flex-direction:column;justify-content:center}
.auth-hero h1{font-size:26px;margin-bottom:10px;line-height:1.25}
.auth-hero p{opacity:.85;font-size:14px}
.auth-hero .badge-list{margin-top:22px;display:flex;flex-direction:column;gap:10px}
.auth-hero .badge-list span{font-size:13px;opacity:.9;display:flex;align-items:center;gap:8px}
.auth-body{padding:40px 36px}
.auth-tabs{display:flex;gap:8px;margin-bottom:22px;background:var(--bg);padding:5px;border-radius:12px}
.auth-tabs button{flex:1;border:0;background:transparent;padding:10px;border-radius:9px;
  font-weight:600;color:var(--muted);cursor:pointer;font-size:14px;transition:.2s}
.auth-tabs button.active{background:var(--card);color:var(--brand);box-shadow:var(--shadow-sm)}

/* ---------- Forms ---------- */
.field{margin-bottom:16px}
.field label{display:block;font-size:13px;font-weight:600;margin-bottom:6px;color:#334155}
.field input,.field select,.field textarea{
  width:100%;padding:12px 14px;border:1.5px solid var(--line);border-radius:11px;
  font-size:15px;font-family:inherit;background:#fff;transition:.15s;color:var(--ink)}
.field input:focus,.field select:focus,.field textarea:focus{
  outline:0;border-color:var(--brand);box-shadow:0 0 0 4px var(--brand-light)}
.field textarea{min-height:100px;resize:vertical}

/* ---------- Buttons ---------- */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;
  padding:12px 20px;border:0;border-radius:11px;font-size:15px;font-weight:600;
  cursor:pointer;transition:.18s;background:var(--brand);color:#fff;text-align:center}
.btn:hover{background:var(--brand-dark);transform:translateY(-1px)}
.btn:active{transform:translateY(0)}
.btn-block{width:100%}
.btn-sm{padding:8px 14px;font-size:13px;border-radius:9px}
.btn-ghost{background:var(--brand-light);color:var(--brand)}
.btn-ghost:hover{background:#e0e7ff}
.btn-danger{background:var(--danger)}.btn-danger:hover{background:#b91c1c}
.btn-success{background:var(--success)}.btn-success:hover{background:#15803d}
.btn-outline{background:#fff;border:1.5px solid var(--line);color:var(--ink)}
.btn-outline:hover{border-color:var(--brand);color:var(--brand);background:#fff}

/* ---------- Topbar ---------- */
.topbar{background:var(--card);box-shadow:var(--shadow-sm);position:sticky;top:0;z-index:50}
.topbar-inner{display:flex;align-items:center;justify-content:space-between;height:62px}
.brand{display:flex;align-items:center;gap:10px;font-weight:800;color:var(--brand);font-size:18px}
.brand .logo{width:36px;height:36px;border-radius:10px;background:linear-gradient(135deg,var(--brand),var(--accent));
  display:flex;align-items:center;justify-content:center;color:#fff;font-weight:800;font-size:15px}
.topbar-user{display:flex;align-items:center;gap:12px;font-size:14px}
.avatar{width:38px;height:38px;border-radius:50%;background:var(--brand-light);color:var(--brand);
  display:flex;align-items:center;justify-content:center;font-weight:700}

/* ---------- Sidebar layout ---------- */
.shell{display:flex;min-height:calc(100vh - 62px)}
.sidebar{width:250px;background:var(--card);border-right:1px solid var(--line);
  padding:18px 12px;flex-shrink:0;transition:.25s}
.sidebar a{display:flex;align-items:center;gap:11px;padding:11px 14px;border-radius:11px;
  color:#475569;font-weight:600;font-size:14px;margin-bottom:4px;transition:.15s}
.sidebar a:hover{background:var(--bg)}
.sidebar a.active{background:var(--brand);color:#fff}
.sidebar a .ic{width:20px;text-align:center}
.main{flex:1;padding:24px;min-width:0}
.page-title{font-size:22px;font-weight:800;margin-bottom:4px}
.page-sub{color:var(--muted);font-size:14px;margin-bottom:22px}

/* ---------- Cards ---------- */
.card{background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow-sm);
  padding:20px;border:1px solid var(--line)}
.card-h{display:flex;align-items:center;justify-content:space-between;margin-bottom:16px}
.card-h h3{font-size:16px;font-weight:700}

/* Stat cards */
.stat{display:flex;align-items:center;gap:16px;padding:20px;border-radius:var(--radius);
  background:var(--card);box-shadow:var(--shadow-sm);border:1px solid var(--line)}
.stat .si{width:52px;height:52px;border-radius:14px;display:flex;align-items:center;
  justify-content:center;font-size:22px;flex-shrink:0}
.stat .sv{font-size:26px;font-weight:800;line-height:1}
.stat .sl{font-size:13px;color:var(--muted)}
.si.i1{background:#eef2ff;color:var(--brand)} .si.i2{background:#ecfeff;color:var(--accent)}
.si.i3{background:#f0fdf4;color:var(--success)} .si.i4{background:#fef3c7;color:var(--warn)}

/* Unit / subject cards */
.unit-card{background:var(--card);border-radius:var(--radius);border:1px solid var(--line);
  box-shadow:var(--shadow-sm);overflow:hidden;transition:.2s;display:flex;flex-direction:column}
.unit-card:hover{box-shadow:var(--shadow);transform:translateY(-3px)}
.unit-card .uc-top{padding:18px 18px 14px;border-bottom:1px solid var(--line);
  background:linear-gradient(135deg,var(--brand-light),#fff)}
.unit-card .uc-tag{display:inline-block;font-size:11px;font-weight:700;padding:3px 9px;border-radius:20px;
  background:var(--brand);color:#fff;margin-bottom:8px;letter-spacing:.3px}
.unit-card .uc-tag.partb{background:var(--accent)}
.unit-card h4{font-size:15px;line-height:1.35}
.unit-card .uc-body{padding:14px 18px;display:flex;gap:8px;flex-wrap:wrap;margin-top:auto}

/* ---------- Tables ---------- */
.table-wrap{overflow-x:auto;border-radius:var(--radius);border:1px solid var(--line);background:#fff}
table{width:100%;border-collapse:collapse;font-size:14px;min-width:520px}
th,td{padding:12px 14px;text-align:left;border-bottom:1px solid var(--line)}
th{background:var(--bg);font-weight:700;font-size:12.5px;text-transform:uppercase;letter-spacing:.4px;color:#475569}
tr:last-child td{border-bottom:0}
tr:hover td{background:#fafbff}

/* ---------- Badges ---------- */
.badge{display:inline-block;padding:4px 10px;border-radius:20px;font-size:12px;font-weight:600}
.badge-green{background:#dcfce7;color:#166534}
.badge-red{background:#fee2e2;color:#991b1b}
.badge-blue{background:#dbeafe;color:#1e40af}
.badge-amber{background:#fef3c7;color:#92400e}
.badge-gray{background:#f1f5f9;color:#475569}

/* ---------- Alerts ---------- */
.alert{padding:13px 16px;border-radius:11px;font-size:14px;margin-bottom:16px;font-weight:500}
.alert-success{background:#dcfce7;color:#166534;border:1px solid #bbf7d0}
.alert-danger{background:#fee2e2;color:#991b1b;border:1px solid #fecaca}
.alert-info{background:var(--brand-light);color:var(--brand-dark);border:1px solid #c7d2fe}

/* ---------- Quiz ---------- */
.quiz-head{display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:12px;
  background:var(--card);padding:16px 20px;border-radius:var(--radius);box-shadow:var(--shadow-sm);margin-bottom:18px}
.timer{font-size:20px;font-weight:800;color:var(--brand);font-variant-numeric:tabular-nums;
  background:var(--brand-light);padding:8px 16px;border-radius:11px}
.timer.warn{color:var(--danger);background:#fee2e2}
.q-block{background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow-sm);
  padding:22px;margin-bottom:16px;border:1px solid var(--line)}
.q-num{font-size:12px;font-weight:700;color:var(--brand);text-transform:uppercase;letter-spacing:.5px}
.q-text{font-size:16px;font-weight:600;margin:6px 0 16px}
.opt{display:flex;align-items:center;gap:12px;padding:13px 16px;border:1.5px solid var(--line);
  border-radius:12px;margin-bottom:10px;cursor:pointer;transition:.15s;font-size:15px}
.opt:hover{border-color:var(--brand);background:var(--brand-light)}
.opt input{width:18px;height:18px;accent-color:var(--brand);cursor:pointer}
.opt.selected{border-color:var(--brand);background:var(--brand-light)}
.opt.correct{border-color:var(--success);background:#f0fdf4}
.opt.wrong{border-color:var(--danger);background:#fef2f2}
.opt .ok{margin-left:auto;font-weight:700;color:var(--success)}
.opt .no{margin-left:auto;font-weight:700;color:var(--danger)}
.opt-letter{width:28px;height:28px;border-radius:8px;background:var(--bg);display:flex;
  align-items:center;justify-content:center;font-weight:700;font-size:13px;flex-shrink:0}

/* result ring */
.result-ring{width:150px;height:150px;border-radius:50%;display:flex;align-items:center;
  justify-content:center;flex-direction:column;margin:0 auto 8px;color:#fff;font-weight:800}
.result-ring .rp{font-size:34px;line-height:1}
.result-ring .rl{font-size:12px;opacity:.9;font-weight:600}

/* ---------- PDF viewer ---------- */
.pdf-frame{width:100%;height:78vh;border:1px solid var(--line);border-radius:var(--radius);background:#fff}

/* ---------- Utilities ---------- */
.flex{display:flex}.items-center{align-items:center}.justify-between{justify-content:space-between}
.gap-8{gap:8px}.gap-12{gap:12px}.gap-16{gap:16px}.wrap{flex-wrap:wrap}
.mb-8{margin-bottom:8px}.mb-16{margin-bottom:16px}.mb-24{margin-bottom:24px}.mt-16{margin-top:16px}
.mt-24{margin-top:24px}.text-center{text-align:center}.text-muted{color:var(--muted)}
.fw-700{font-weight:700}.fs-13{font-size:13px}.fs-18{font-size:18px}.hidden{display:none}
.divider{height:1px;background:var(--line);margin:16px 0}
.chip{display:inline-flex;align-items:center;gap:6px;padding:5px 12px;border-radius:20px;
  background:var(--bg);font-size:12.5px;font-weight:600;color:#475569}

/* ---------- Mobile hamburger ---------- */
.hamb{display:none;background:none;border:0;font-size:24px;cursor:pointer;color:var(--brand)}
.overlay{display:none;position:fixed;inset:0;background:rgba(0,0,0,.4);z-index:40}

/* ============================================================
   RESPONSIVE — mobile-first breakpoints
   ============================================================ */
@media (max-width:860px){
  .auth-card{grid-template-columns:1fr;max-width:440px}
  .auth-hero{display:none}
  .auth-body{padding:32px 24px}
}
@media (max-width:768px){
  .hamb{display:block}
  .sidebar{position:fixed;left:-260px;top:62px;bottom:0;z-index:45;
    box-shadow:8px 0 30px rgba(0,0,0,.15);overflow-y:auto}
  .sidebar.open{left:0}
  .overlay.show{display:block}
  .main{padding:16px}
  .page-title{font-size:19px}
  .topbar-user .uname{display:none}
  .quiz-head{padding:14px}
  .timer{font-size:17px;padding:6px 12px}
}
@media (max-width:480px){
  .container{padding:0 12px}
  .stat{padding:16px;gap:12px}
  .stat .sv{font-size:22px}
  .stat .si{width:44px;height:44px;font-size:18px}
  .card{padding:16px}
  .q-block{padding:16px}
  .q-text{font-size:15px}
  .opt{padding:11px 13px;font-size:14px}
  .btn{padding:11px 16px;font-size:14px}
  .auth-body{padding:26px 18px}
}