/* ComPrep LMS — design system (no build step). Light/dark via [data-theme]. */
:root{
  --bg:#f6f7fb; --surface:#ffffff; --surface-2:#f0f2f8; --border:#e4e7ee;
  --text:#1a1d29; --muted:#6b7280; --primary:#4f46e5; --primary-600:#4338ca;
  --primary-soft:#eef0fe; --success:#16a34a; --success-soft:#e8f7ee;
  --warn:#d97706; --warn-soft:#fdf3e3; --danger:#dc2626; --danger-soft:#fbeaea;
  --accent:#0ea5e9; --radius:14px; --radius-sm:10px; --shadow:0 1px 3px rgba(20,20,40,.06),0 8px 24px rgba(20,20,40,.05);
  --shadow-lg:0 12px 40px rgba(20,20,40,.12); --sidebar:#0f1222; --sidebar-text:#c3c8da;
}
[data-theme="dark"]{
  --bg:#0b0d17; --surface:#14172a; --surface-2:#1c2138; --border:#262c45;
  --text:#e8eaf2; --muted:#8b91a7; --primary:#7c83ff; --primary-600:#6b73ff;
  --primary-soft:#1e2240; --success:#34d399; --success-soft:#11261f;
  --warn:#fbbf24; --warn-soft:#2a2110; --danger:#f87171; --danger-soft:#2a1414;
  --accent:#38bdf8; --shadow:0 1px 3px rgba(0,0,0,.4); --shadow-lg:0 16px 50px rgba(0,0,0,.5);
  --sidebar:#080a14; --sidebar-text:#9aa0b8;
}
*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{background:var(--bg);color:var(--text);font-family:'Inter',-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;font-size:14.5px;line-height:1.55;-webkit-font-smoothing:antialiased;transition:background .3s,color .3s}
a{color:var(--primary);text-decoration:none}
h1,h2,h3,h4{margin:0 0 .4em;line-height:1.25;font-weight:700;letter-spacing:-.01em}
h1{font-size:1.6rem}h2{font-size:1.25rem}h3{font-size:1.05rem}
.muted{color:var(--muted)}.small{font-size:.82rem}.center{text-align:center}
.mono{font-family:ui-monospace,SFMono-Regular,Menlo,monospace}

/* layout */
.app{display:grid;grid-template-columns:248px 1fr;min-height:100vh}
.sidebar{background:var(--sidebar);color:var(--sidebar-text);padding:18px 14px;position:sticky;top:0;height:100vh;overflow-y:auto}
.sidebar .brand{display:flex;align-items:center;gap:10px;color:#fff;font-weight:800;font-size:1.1rem;padding:6px 10px 18px}
.sidebar .brand .dot{width:28px;height:28px;border-radius:8px;background:linear-gradient(135deg,var(--primary),var(--accent));display:grid;place-items:center;color:#fff;font-size:.9rem}
.nav-group{margin:14px 0 6px;font-size:.68rem;text-transform:uppercase;letter-spacing:.08em;color:#5b6178;padding:0 10px}
.nav a{display:flex;align-items:center;gap:10px;padding:9px 11px;border-radius:10px;color:var(--sidebar-text);font-weight:500;transition:.15s;margin-bottom:2px}
.nav a:hover{background:rgba(255,255,255,.06);color:#fff}
.nav a.active{background:linear-gradient(135deg,var(--primary),var(--primary-600));color:#fff;box-shadow:0 6px 16px rgba(79,70,229,.35)}
.nav a svg{width:18px;height:18px;flex:none}
.main{display:flex;flex-direction:column;min-width:0}
.topbar{display:flex;align-items:center;justify-content:space-between;padding:14px 26px;background:var(--surface);border-bottom:1px solid var(--border);position:sticky;top:0;z-index:20}
.content{padding:26px;max-width:1240px;width:100%;margin:0 auto;animation:fadeUp .4s ease}
@media(max-width:880px){.app{grid-template-columns:1fr}.sidebar{display:none}}

/* cards / grid */
.card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow);padding:20px}
.card+.card{margin-top:16px}
.grid{display:grid;gap:16px}
.grid-2{grid-template-columns:repeat(2,1fr)}.grid-3{grid-template-columns:repeat(3,1fr)}
.grid-4{grid-template-columns:repeat(4,1fr)}
@media(max-width:980px){.grid-3,.grid-4{grid-template-columns:repeat(2,1fr)}}
@media(max-width:620px){.grid-2,.grid-3,.grid-4{grid-template-columns:1fr}}
.row{display:flex;gap:12px;align-items:center}.between{justify-content:space-between}.wrap{flex-wrap:wrap}
.stack{display:flex;flex-direction:column;gap:14px}

/* stat tiles */
.stat{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:18px;box-shadow:var(--shadow);transition:transform .2s,box-shadow .2s}
.stat:hover{transform:translateY(-3px);box-shadow:var(--shadow-lg)}
.stat .label{font-size:.78rem;color:var(--muted);font-weight:600;text-transform:uppercase;letter-spacing:.04em}
.stat .value{font-size:1.7rem;font-weight:800;margin-top:6px}

/* buttons */
.btn{display:inline-flex;align-items:center;gap:8px;border:1px solid transparent;border-radius:10px;padding:9px 16px;font-weight:600;font-size:.9rem;cursor:pointer;transition:.18s;background:var(--surface-2);color:var(--text)}
.btn:hover{transform:translateY(-1px)}
.btn-primary{background:linear-gradient(135deg,var(--primary),var(--primary-600));color:#fff;box-shadow:0 6px 18px rgba(79,70,229,.32)}
.btn-ghost{background:transparent;border-color:var(--border)}
.btn-danger{background:var(--danger-soft);color:var(--danger)}
.btn-success{background:var(--success);color:#fff}
.btn-sm{padding:6px 11px;font-size:.82rem;border-radius:8px}
.btn-block{width:100%;justify-content:center}
.btn:disabled{opacity:.5;cursor:not-allowed;transform:none}

/* badges */
.badge{display:inline-flex;align-items:center;gap:5px;padding:3px 10px;border-radius:999px;font-size:.74rem;font-weight:600}
.badge-primary{background:var(--primary-soft);color:var(--primary)}
.badge-success{background:var(--success-soft);color:var(--success)}
.badge-warn{background:var(--warn-soft);color:var(--warn)}
.badge-danger{background:var(--danger-soft);color:var(--danger)}
.badge-muted{background:var(--surface-2);color:var(--muted)}

/* forms */
.field{margin-bottom:15px}
.field label{display:block;font-weight:600;font-size:.85rem;margin-bottom:6px}
.input,select,textarea{width:100%;padding:10px 12px;border:1px solid var(--border);border-radius:10px;background:var(--surface);color:var(--text);font:inherit;transition:.15s}
.input:focus,select:focus,textarea:focus{outline:none;border-color:var(--primary);box-shadow:0 0 0 3px var(--primary-soft)}
textarea{min-height:90px;resize:vertical}
.check{display:flex;align-items:center;gap:9px;font-weight:500}
.check input{width:18px;height:18px;accent-color:var(--primary)}
.err{color:var(--danger);font-size:.8rem;margin-top:5px}
.help{color:var(--muted);font-size:.8rem;margin-top:5px}

/* table */
.table{width:100%;border-collapse:collapse}
.table th{text-align:left;font-size:.74rem;text-transform:uppercase;letter-spacing:.04em;color:var(--muted);padding:11px 12px;border-bottom:1px solid var(--border)}
.table td{padding:12px;border-bottom:1px solid var(--border);vertical-align:middle}
.table tr:hover td{background:var(--surface-2)}
.table tr:last-child td{border-bottom:none}

/* alerts */
.alert{padding:12px 16px;border-radius:10px;margin-bottom:16px;font-weight:500;animation:slideIn .3s}
.alert-ok{background:var(--success-soft);color:var(--success)}
.alert-err{background:var(--danger-soft);color:var(--danger)}

/* progress */
.progress{height:8px;background:var(--surface-2);border-radius:999px;overflow:hidden}
.progress>span{display:block;height:100%;background:linear-gradient(90deg,var(--primary),var(--accent));border-radius:999px;transition:width .6s ease}
.ring{--p:0;width:54px;height:54px;border-radius:50%;background:conic-gradient(var(--primary) calc(var(--p)*1%),var(--surface-2) 0);display:grid;place-items:center}
.ring>b{width:40px;height:40px;border-radius:50%;background:var(--surface);display:grid;place-items:center;font-size:.78rem;font-weight:700}

/* lesson list */
.lesson-item{display:flex;align-items:center;gap:12px;padding:12px 14px;border:1px solid var(--border);border-radius:12px;margin-bottom:8px;transition:.18s;background:var(--surface)}
.lesson-item:hover{border-color:var(--primary);transform:translateX(3px)}
.lesson-item.locked{opacity:.62}
.lesson-ico{width:36px;height:36px;border-radius:9px;display:grid;place-items:center;background:var(--primary-soft);color:var(--primary);flex:none}
.lesson-item.locked .lesson-ico{background:var(--surface-2);color:var(--muted)}

/* tabs */
.tabs{display:flex;gap:6px;border-bottom:1px solid var(--border);margin-bottom:18px;flex-wrap:wrap}
.tabs a,.tabs button{padding:9px 14px;border:none;background:none;color:var(--muted);font-weight:600;cursor:pointer;border-bottom:2px solid transparent}
.tabs a.active,.tabs button.active{color:var(--primary);border-bottom-color:var(--primary)}

/* video */
.video-wrap{position:relative;aspect-ratio:16/9;background:#000;border-radius:14px;overflow:hidden}
.video-wrap iframe{width:100%;height:100%;border:0}
.wm{position:absolute;bottom:12px;right:12px;color:rgba(255,255,255,.5);font-size:.72rem;pointer-events:none;text-shadow:0 1px 3px rgba(0,0,0,.8);z-index:3}
.locked-panel{aspect-ratio:16/9;border-radius:14px;display:grid;place-items:center;text-align:center;background:var(--surface-2);border:1px dashed var(--border);padding:30px}

/* test option */
.opt{display:flex;align-items:flex-start;gap:11px;padding:13px 15px;border:1.5px solid var(--border);border-radius:11px;margin-bottom:10px;cursor:pointer;transition:.15s}
.opt:hover{border-color:var(--primary)}
.opt.sel{border-color:var(--primary);background:var(--primary-soft)}
.opt .key{width:26px;height:26px;border-radius:7px;background:var(--surface-2);display:grid;place-items:center;font-weight:700;flex:none}
.opt.sel .key{background:var(--primary);color:#fff}
.q-nav{display:flex;flex-wrap:wrap;gap:7px}
.q-nav button{width:38px;height:38px;border-radius:9px;border:1px solid var(--border);background:var(--surface);font-weight:700;cursor:pointer}
.q-nav button.answered{background:var(--success);color:#fff;border-color:var(--success)}
.q-nav button.review{background:var(--warn);color:#fff;border-color:var(--warn)}
.q-nav button.current{outline:2px solid var(--primary);outline-offset:1px}

/* misc */
.tag{font-size:.72rem;padding:2px 8px;border-radius:6px;background:var(--surface-2);color:var(--muted);font-weight:600}
.divider{height:1px;background:var(--border);margin:18px 0}
.empty{text-align:center;padding:48px 20px;color:var(--muted)}
.empty svg{width:48px;height:48px;opacity:.4;margin-bottom:12px}
.avatar{width:38px;height:38px;border-radius:50%;background:linear-gradient(135deg,var(--primary),var(--accent));color:#fff;display:grid;place-items:center;font-weight:700}
.icon-btn{width:38px;height:38px;border-radius:10px;border:1px solid var(--border);background:var(--surface);display:grid;place-items:center;cursor:pointer;color:var(--text)}
.icon-btn:hover{background:var(--surface-2)}

/* auth */
.auth-wrap{min-height:100vh;display:grid;place-items:center;padding:24px;background:radial-gradient(1200px 600px at 70% -10%,var(--primary-soft),transparent),var(--bg)}
.auth-card{width:100%;max-width:420px;animation:fadeUp .5s ease}

/* chat */
.bubble{max-width:78%;padding:11px 15px;border-radius:14px;margin-bottom:10px;animation:slideIn .25s}
.bubble.user{background:linear-gradient(135deg,var(--primary),var(--primary-600));color:#fff;margin-left:auto;border-bottom-right-radius:4px}
.bubble.ai{background:var(--surface-2);border-bottom-left-radius:4px}
.bubble.faculty{background:var(--warn-soft);border-bottom-left-radius:4px}
.bubble .who{font-size:.7rem;opacity:.7;font-weight:700;margin-bottom:3px;text-transform:uppercase}

/* animations */
@keyframes fadeUp{from{opacity:0;transform:translateY(12px)}to{opacity:1;transform:none}}
@keyframes slideIn{from{opacity:0;transform:translateX(-8px)}to{opacity:1;transform:none}}
@keyframes shimmer{0%{background-position:-400px 0}100%{background-position:400px 0}}
.skeleton{background:linear-gradient(90deg,var(--surface-2) 25%,var(--border) 37%,var(--surface-2) 63%);background-size:800px 100%;animation:shimmer 1.4s infinite}
.pop{animation:fadeUp .35s ease both}
.delay-1{animation-delay:.05s}.delay-2{animation-delay:.1s}.delay-3{animation-delay:.15s}.delay-4{animation-delay:.2s}