:root {
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --primary-light: #dbeafe;
  --success: #16a34a;
  --success-light: #dcfce7;
  --danger: #dc2626;
  --danger-light: #fee2e2;
  --warning: #d97706;
  --warning-light: #fef3c7;
  --neutral-900: #0f172a;
  --neutral-700: #334155;
  --neutral-500: #64748b;
  --neutral-300: #cbd5e1;
  --neutral-100: #f1f5f9;
  --neutral-50: #f8fafc;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, .05);
  --shadow: 0 4px 12px rgba(0, 0, 0, .08);
  --shadow-lg: 0 10px 30px rgba(0, 0, 0, .12);
  --radius: 12px;
  --radius-sm: 8px;
}

* { box-sizing: border-box; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background: linear-gradient(135deg, #eef2ff 0%, #f8fafc 100%);
  color: var(--neutral-900);
  min-height: 100vh;
  margin: 0;
}

/* ---------- Top nav ---------- */
.app-nav {
  background: #fff;
  box-shadow: var(--shadow-sm);
  padding: 14px 28px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--neutral-100);
}
.app-nav .brand {
  font-weight: 700;
  font-size: 18px;
  color: var(--primary);
  letter-spacing: -.02em;
}
.app-nav .brand span { color: var(--neutral-700); font-weight: 500; }
.app-nav .nav-actions { display: flex; gap: 10px; align-items: center; }
.app-nav .user-pill {
  background: var(--primary-light);
  color: var(--primary-dark);
  padding: 6px 12px;
  border-radius: 999px;
  font-size: 13px;
  font-weight: 600;
}

/* ---------- Layout ---------- */
.page {
  max-width: 1100px;
  margin: 32px auto;
  padding: 0 20px;
}
.page-narrow { max-width: 560px; margin: 60px auto; padding: 0 20px; }

.card {
  background: #fff;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 28px;
  margin-bottom: 20px;
}
.card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 20px;
  flex-wrap: wrap;
  gap: 12px;
}
.card-title {
  font-size: 22px;
  font-weight: 700;
  margin: 0;
  color: var(--neutral-900);
  letter-spacing: -.01em;
}
.card-subtitle {
  color: var(--neutral-500);
  font-size: 14px;
  margin: 4px 0 0;
}

/* ---------- Forms ---------- */
.field { margin-bottom: 16px; }
.field label {
  display: block;
  font-size: 13px;
  font-weight: 600;
  color: var(--neutral-700);
  margin-bottom: 6px;
}
.field input,
.field select,
.field textarea {
  width: 100%;
  padding: 10px 14px;
  border: 1.5px solid var(--neutral-300);
  border-radius: var(--radius-sm);
  font-size: 15px;
  font-family: inherit;
  transition: border-color .15s, box-shadow .15s;
  background: #fff;
}
.field input:focus,
.field select:focus,
.field textarea:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, .15);
}
.field textarea { resize: vertical; min-height: 80px; }
.field-row { display: flex; gap: 12px; }
.field-row .field { flex: 1; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 10px 18px;
  font-size: 14px;
  font-weight: 600;
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: transform .1s, box-shadow .15s, background .15s;
  text-decoration: none;
}
.btn:active { transform: translateY(1px); }
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-dark); box-shadow: var(--shadow); }
.btn-secondary { background: var(--neutral-100); color: var(--neutral-700); }
.btn-secondary:hover { background: var(--neutral-300); }
.btn-success { background: var(--success); color: #fff; }
.btn-success:hover { filter: brightness(0.95); }
.btn-danger { background: var(--danger); color: #fff; }
.btn-danger:hover { filter: brightness(0.95); }
.btn-ghost { background: transparent; color: var(--neutral-700); }
.btn-ghost:hover { background: var(--neutral-100); }
.btn-sm { padding: 6px 12px; font-size: 13px; }
.btn-block { width: 100%; }

/* ---------- Alerts ---------- */
.alert {
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  margin-bottom: 16px;
  font-size: 14px;
  border-left: 4px solid;
}
.alert-error   { background: var(--danger-light); color: var(--danger); border-color: var(--danger); }
.alert-success { background: var(--success-light); color: var(--success); border-color: var(--success); }
.alert-info    { background: var(--primary-light); color: var(--primary-dark); border-color: var(--primary); }

/* ---------- Tabs ---------- */
.tabs {
  display: flex;
  border-bottom: 2px solid var(--neutral-100);
  margin-bottom: 20px;
}
.tab {
  padding: 10px 18px;
  font-size: 14px;
  font-weight: 600;
  color: var(--neutral-500);
  background: none;
  border: none;
  border-bottom: 2px solid transparent;
  margin-bottom: -2px;
  cursor: pointer;
  transition: color .15s, border-color .15s;
}
.tab:hover { color: var(--neutral-700); }
.tab.active { color: var(--primary); border-color: var(--primary); }

/* ---------- Tables ---------- */
.tbl {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
}
.tbl th, .tbl td {
  padding: 12px 14px;
  text-align: left;
  border-bottom: 1px solid var(--neutral-100);
}
.tbl th {
  background: var(--neutral-50);
  font-weight: 600;
  color: var(--neutral-700);
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: .03em;
}
.tbl tbody tr:hover { background: var(--neutral-50); }
.tbl-actions { display: flex; gap: 6px; }

/* ---------- Quiz list cards ---------- */
.quiz-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 16px; }
.quiz-card {
  background: #fff;
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: var(--shadow-sm);
  border: 1.5px solid var(--neutral-100);
  transition: transform .15s, box-shadow .15s, border-color .15s;
  display: flex;
  flex-direction: column;
}
.quiz-card:hover { transform: translateY(-2px); box-shadow: var(--shadow); border-color: var(--primary-light); }
.quiz-card h3 { margin: 0 0 8px; font-size: 17px; color: var(--neutral-900); }
.quiz-card .desc { color: var(--neutral-500); font-size: 14px; flex-grow: 1; margin-bottom: 14px; }
.quiz-card .meta {
  display: flex;
  gap: 12px;
  font-size: 13px;
  color: var(--neutral-500);
  margin-bottom: 14px;
}
.quiz-card .meta-item { display: flex; align-items: center; gap: 4px; }

/* ---------- Quiz player ---------- */
.quiz-header {
  background: var(--primary);
  color: #fff;
  padding: 24px 28px;
  border-radius: var(--radius);
  margin-bottom: 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 14px;
}
.quiz-header h2 { margin: 0; font-size: 22px; }
.quiz-header .meta { display: flex; gap: 18px; font-size: 14px; opacity: .9; }

.timer-pill {
  background: rgba(255, 255, 255, .15);
  padding: 8px 16px;
  border-radius: 999px;
  font-weight: 700;
  font-size: 18px;
  font-variant-numeric: tabular-nums;
  min-width: 100px;
  text-align: center;
}
.timer-pill.warning { background: var(--warning); color: #fff; }
.timer-pill.danger  { background: var(--danger);  color: #fff; animation: pulse-bg 1s infinite; }
@keyframes pulse-bg { 0%, 100% { opacity: 1; } 50% { opacity: .65; } }

.progress {
  height: 8px;
  background: var(--neutral-100);
  border-radius: 999px;
  overflow: hidden;
  margin-bottom: 20px;
}
.progress-bar {
  height: 100%;
  background: linear-gradient(90deg, var(--primary), var(--success));
  width: 0;
  transition: width .3s ease;
}

.question-text {
  font-size: 18px;
  line-height: 1.55;
  color: var(--neutral-900);
  margin: 0 0 24px;
  font-weight: 500;
}

.choice-list { display: flex; flex-direction: column; gap: 10px; }
.choice {
  padding: 14px 18px;
  background: #fff;
  border: 2px solid var(--neutral-300);
  border-radius: var(--radius-sm);
  cursor: pointer;
  font-size: 15px;
  transition: border-color .15s, background .15s, transform .1s;
  display: flex;
  gap: 12px;
  align-items: flex-start;
  text-align: left;
}
.choice:hover { border-color: var(--primary); background: var(--neutral-50); }
.choice .key {
  background: var(--neutral-100);
  color: var(--neutral-700);
  font-weight: 700;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  font-size: 13px;
}
.choice.selected { border-color: var(--primary); background: var(--primary-light); }
.choice.selected .key { background: var(--primary); color: #fff; }
.choice.correct { border-color: var(--success); background: var(--success-light); }
.choice.correct .key { background: var(--success); color: #fff; }
.choice.wrong { border-color: var(--danger); background: var(--danger-light); }
.choice.wrong .key { background: var(--danger); color: #fff; }

.quiz-actions {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 24px;
  gap: 12px;
}

/* ---------- Score view ---------- */
.score-display {
  text-align: center;
  padding: 30px 20px;
}
.score-circle {
  width: 140px;
  height: 140px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary), var(--success));
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  margin: 0 auto 20px;
  box-shadow: var(--shadow-lg);
}
.score-circle .num { font-size: 42px; font-weight: 800; line-height: 1; }
.score-circle .label { font-size: 13px; opacity: .9; margin-top: 4px; }

/* ---------- Empty states ---------- */
.empty {
  text-align: center;
  padding: 40px 20px;
  color: var(--neutral-500);
}
.empty .empty-icon { font-size: 42px; margin-bottom: 8px; }

/* ---------- Portal home ---------- */
.portal-hero {
  text-align: center;
  margin: 80px auto 40px;
  max-width: 720px;
  padding: 0 20px;
}
.portal-hero h1 {
  font-size: 42px;
  font-weight: 800;
  letter-spacing: -.025em;
  margin: 0 0 12px;
  background: linear-gradient(135deg, var(--primary), var(--success));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.portal-hero p { color: var(--neutral-500); font-size: 18px; margin: 0; }
.portal-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 24px;
  max-width: 720px;
  margin: 0 auto;
  padding: 0 20px 60px;
}
.portal-card {
  display: block;
  background: #fff;
  padding: 32px 28px;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  text-decoration: none;
  color: var(--neutral-900);
  transition: transform .2s, box-shadow .2s;
  border: 2px solid transparent;
}
.portal-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--primary);
}
.portal-card .icon {
  font-size: 38px;
  margin-bottom: 14px;
  display: block;
}
.portal-card h3 { margin: 0 0 6px; font-size: 20px; }
.portal-card p { color: var(--neutral-500); font-size: 14px; margin: 0; }

/* ---------- Misc ---------- */
.hidden { display: none !important; }
.text-muted { color: var(--neutral-500); }
.flex { display: flex; gap: 12px; align-items: center; }
.flex-between { display: flex; justify-content: space-between; align-items: center; gap: 12px; flex-wrap: wrap; }
.spacer-md { height: 16px; }
.badge {
  display: inline-block;
  padding: 2px 10px;
  border-radius: 999px;
  font-size: 12px;
  font-weight: 600;
}
.badge-success { background: var(--success-light); color: var(--success); }
.badge-warning { background: var(--warning-light); color: var(--warning); }
.badge-neutral { background: var(--neutral-100); color: var(--neutral-700); }

/* ---------- Analytics dashboard ---------- */
.stat-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px;
  margin-bottom: 20px;
}
.stat-card {
  background: #fff;
  border-radius: var(--radius);
  padding: 20px 22px;
  box-shadow: var(--shadow-sm);
  border-left: 4px solid var(--primary);
  display: flex;
  flex-direction: column;
  gap: 4px;
}
.stat-card.success { border-left-color: var(--success); }
.stat-card.warning { border-left-color: var(--warning); }
.stat-card.danger  { border-left-color: var(--danger); }
.stat-card .stat-label {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: .04em;
  color: var(--neutral-500);
  font-weight: 600;
}
.stat-card .stat-value {
  font-size: 32px;
  font-weight: 800;
  color: var(--neutral-900);
  letter-spacing: -.02em;
  line-height: 1;
  font-variant-numeric: tabular-nums;
}
.stat-card .stat-sub {
  font-size: 13px;
  color: var(--neutral-500);
  margin-top: 2px;
}

.grid-2 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 20px;
}
.grid-2 > .card { margin-bottom: 0; }

.rank-list { display: flex; flex-direction: column; gap: 10px; }
.rank-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  background: var(--neutral-50);
  border: 1px solid var(--neutral-100);
}
.rank-item .rank-num {
  width: 28px; height: 28px;
  border-radius: 50%;
  background: var(--primary);
  color: #fff;
  display: flex; align-items: center; justify-content: center;
  font-weight: 700; font-size: 13px;
  flex-shrink: 0;
}
.rank-item.gold   .rank-num { background: #f59e0b; }
.rank-item.silver .rank-num { background: #94a3b8; }
.rank-item.bronze .rank-num { background: #b45309; }
.rank-item .rank-body { flex: 1; min-width: 0; }
.rank-item .rank-title {
  font-weight: 600; color: var(--neutral-900);
  overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
}
.rank-item .rank-sub {
  font-size: 13px; color: var(--neutral-500);
}
.rank-item .rank-value {
  font-weight: 700; color: var(--primary);
  font-variant-numeric: tabular-nums;
  flex-shrink: 0;
}
.rank-item.danger .rank-value { color: var(--danger); }

/* Landing page features */
.features {
  max-width: 960px;
  margin: 40px auto 60px;
  padding: 0 20px;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 20px;
}
.feature {
  background: rgba(255, 255, 255, .7);
  backdrop-filter: blur(8px);
  border-radius: var(--radius);
  padding: 22px;
  border: 1px solid var(--neutral-100);
}
.feature .feature-icon {
  font-size: 28px;
  margin-bottom: 8px;
  display: block;
}
.feature h4 { margin: 0 0 6px; font-size: 16px; color: var(--neutral-900); }
.feature p { margin: 0; font-size: 14px; color: var(--neutral-500); line-height: 1.5; }

.app-footer {
  text-align: center;
  padding: 30px 20px;
  color: var(--neutral-500);
  font-size: 13px;
  border-top: 1px solid var(--neutral-100);
  margin-top: 40px;
}

@media (max-width: 600px) {
  .field-row { flex-direction: column; gap: 0; }
  .quiz-header { flex-direction: column; align-items: flex-start; }
  .portal-hero h1 { font-size: 32px; }
  .stat-card .stat-value { font-size: 26px; }
}