:root{
  --bg: #0f1724;
  --panel: #0b1220;
  --card: #0f1724;
  --muted: #9aa6b2;
  --text: #e6eef6;
  --accent: #7ee787;
  --accent-2: #60a5fa;
  --danger: #ff6b6b;
  --glass: rgba(255,255,255,0.04);
  --radius: 14px;
}

/* Light theme variables */
:root.light{
  --bg: #f6f8fb;
  --panel: #ffffff;
  --card: #ffffff;
  --muted: #6b7280;
  --text: #0b1220;
  --accent: #0ea5a3;
  --accent-2: #2563eb;
  --danger: #ef4444;
  --glass: rgba(15,23,42,0.03);
}

*{box-sizing:border-box;font-family:Inter, ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial;}
html,body{height:100%;margin:0;background:linear-gradient(180deg,var(--bg),rgba(0,0,0,0.02));color:var(--text);-webkit-font-smoothing:antialiased;}
.app-shell{min-height:100%;display:flex;flex-direction:column;}
.topbar{display:flex;align-items:center;justify-content:space-between;padding:18px 24px;background:linear-gradient(180deg,rgba(255,255,255,0.02),transparent);backdrop-filter:blur(6px)}
.brand{display:flex;gap:12px;align-items:center}
.logo{width:44px;height:44px;border-radius:10px;background:linear-gradient(135deg,var(--accent-2),var(--accent));display:flex;align-items:center;justify-content:center;font-weight:700;color:#021;box-shadow:0 6px 18px rgba(2,6,23,0.6)}
.brand h1{margin:0;font-size:16px}
.muted{color:var(--muted);font-size:13px}
.nav{display:flex;gap:10px;align-items:center}
.navlink{padding:8px 12px;border-radius:10px;color:var(--muted);text-decoration:none;font-weight:600}
.navlink.active{background:var(--glass);color:var(--text)}

.container{max-width:1100px;margin:28px auto;padding:0 20px;flex:1}
.card{background:linear-gradient(180deg, rgba(255,255,255,0.02), transparent);border-radius:var(--radius);padding:18px;box-shadow:0 6px 28px rgba(2,6,23,0.45);margin-bottom:18px}
.hero{display:flex;flex-direction:column;gap:12px;padding:28px}
.lead{color:var(--muted)}
.cta-row{display:flex;gap:12px}
.btn{padding:10px 14px;border-radius:12px;border:none;background:transparent;color:var(--text);cursor:pointer;font-weight:700;box-shadow:inset 0 0 0 1px rgba(255,255,255,0.03)}
.btn:hover{transform:translateY(-2px);transition:all 0.16s ease;}
.btn.primary{background:linear-gradient(90deg,var(--accent),var(--accent-2));color:#022;border-radius:12px}
.btn.destructive{background:linear-gradient(90deg,var(--danger),#ff8a8a);color:#fff}
.btn.tiny{padding:6px 8px;border-radius:8px;font-size:13px}
.row{display:flex;gap:12px;align-items:center}
.spaced{justify-content:space-between}
.grid-3{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}
.grid-cards{display:grid;grid-template-columns:repeat(auto-fill,minmax(240px,1fr));gap:12px}
.mini-card{padding:12px;border-radius:12px;background:linear-gradient(180deg, rgba(255,255,255,0.01), transparent);box-shadow:0 6px 18px rgba(2,6,23,0.3)}
.mini-card .q{font-weight:700;margin-bottom:8px}
.mini-card .a{color:var(--muted);font-size:13px;margin-bottom:8px}
.mini-card .meta{font-size:12px;color:var(--muted);margin-bottom:8px}
.actions{display:flex;gap:6px}

.label{display:block;font-size:13px;margin-bottom:6px;color:var(--muted)}
.input, .textarea, select{width:100%;padding:10px;border-radius:10px;border:none;background:rgba(255,255,255,0.02);color:var(--text)}
.textarea{min-height:160px;resize:vertical}
.large{min-height:360px}
.small{padding:12px}
.empty{padding:30px;text-align:center;color:var(--muted)}
.study-card{display:flex;flex-direction:column}
.large-text{font-size:20px;font-weight:700}
.answer{margin-top:12px;padding:12px;border-radius:8px;background:rgba(255,255,255,0.02)}
.hidden{display:none}
.ratings .btn{min-width:84px}
.grid-quiz{display:grid;grid-template-columns:repeat(auto-fill,minmax(320px,1fr));gap:12px}
.qcard{padding:14px}
.choice{display:block;padding:8px;border-radius:10px;margin-bottom:6px;background:rgba(255,255,255,0.02)}
.footer{padding:18px;text-align:center;color:var(--muted);font-size:13px}

/* responsiveness */
@media (max-width:900px){
  .grid-3{grid-template-columns:1fr}
  .nav{display:none}
  .container{padding:14px}
}