:root {
  --primary: #2f5fd6;
  --primary-dark: #1e3f9c;
  --accent: #f2994a;
  --bg: #f4f6fb;
  --card-bg: #ffffff;
  --text: #1f2433;
  --text-muted: #6b7280;
  --border: #e2e6ef;
  --success: #1e9e58;
  --danger: #d64545;
  --radius: 10px;
  --shadow: 0 4px 16px rgba(31, 36, 51, 0.08);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: 'Segoe UI', Roboto, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
}

a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }

.container {
  max-width: 960px;
  margin: 0 auto;
  padding: 24px 20px 60px;
}

.topbar {
  background: linear-gradient(120deg, var(--primary), var(--primary-dark));
  color: #fff;
  padding: 18px 20px;
  box-shadow: var(--shadow);
}

.topbar .container {
  padding: 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.topbar h1 {
  font-size: 1.3rem;
  margin: 0;
}

.topbar a { color: #fff; }

.card {
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 28px;
  margin-bottom: 24px;
}

.card h2 {
  margin-top: 0;
}

label {
  display: block;
  font-weight: 600;
  margin-bottom: 6px;
  margin-top: 16px;
}

input[type=text], input[type=password], input[type=number], select, textarea {
  width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 1rem;
  background: #fff;
  color: var(--text);
}

textarea { resize: vertical; min-height: 80px; }

.btn {
  display: inline-block;
  background: var(--primary);
  color: #fff;
  border: none;
  padding: 11px 22px;
  border-radius: 8px;
  font-size: 1rem;
  cursor: pointer;
  margin-top: 20px;
}

.btn:hover { background: var(--primary-dark); text-decoration: none; }

.btn-secondary { background: #6b7280; }
.btn-secondary:hover { background: #4b5563; }

.btn-danger { background: var(--danger); }
.btn-danger:hover { background: #b23636; }

.btn-small { padding: 6px 14px; font-size: 0.85rem; margin-top: 0; }

.alert {
  padding: 12px 16px;
  border-radius: 8px;
  margin-bottom: 18px;
  font-size: 0.95rem;
}

.alert-error { background: #fde8e8; color: var(--danger); border: 1px solid #f5b5b5; }
.alert-success { background: #e6f6ed; color: var(--success); border: 1px solid #a9e0c1; }

.category-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px;
  margin-top: 10px;
}

.category-option {
  border: 2px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  text-align: center;
  cursor: pointer;
  transition: 0.15s;
  background: #fafbfe;
}

.category-option:hover { border-color: var(--primary); }
.category-option input { display: none; }
.category-option.selected { border-color: var(--primary); background: #eef2fd; }
.category-option .cat-name { font-weight: 700; font-size: 1.05rem; }
.category-option .cat-meta { color: var(--text-muted); font-size: 0.85rem; margin-top: 4px; }

.exam-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: 20px;
}

#timer {
  background: var(--primary-dark);
  color: #fff;
  padding: 8px 16px;
  border-radius: 8px;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

#timer.time-warning { background: var(--danger); }

.question-block {
  border-bottom: 1px solid var(--border);
  padding: 20px 0;
}

.question-block:last-child { border-bottom: none; }

.question-num {
  font-weight: 700;
  color: var(--primary-dark);
  margin-bottom: 6px;
}

.option-row {
  display: block;
  padding: 10px 14px;
  border: 1px solid var(--border);
  border-radius: 8px;
  margin-top: 8px;
  cursor: pointer;
}

.option-row:hover { background: #f7f9fd; }
.option-row input { margin-right: 10px; }

table.data-table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 10px;
}

table.data-table th, table.data-table td {
  padding: 10px 12px;
  border-bottom: 1px solid var(--border);
  text-align: left;
  font-size: 0.92rem;
}

table.data-table th { background: #f5f7fb; }

.badge {
  display: inline-block;
  padding: 3px 10px;
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: 700;
  background: #eef2fd;
  color: var(--primary-dark);
}

.score-display {
  text-align: center;
  padding: 30px 0;
}

.score-display .big-score {
  font-size: 3rem;
  font-weight: 800;
  color: var(--primary);
}

.filter-bar {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 16px;
  align-items: flex-end;
}

.filter-bar > div { flex: 1; min-width: 160px; }

.admin-nav {
  display: flex;
  gap: 18px;
  flex-wrap: wrap;
}

.stat-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 16px;
  margin-bottom: 24px;
}

.stat-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 20px;
  text-align: center;
}

.stat-card .num { font-size: 1.8rem; font-weight: 800; color: var(--primary); }
.stat-card .label { color: var(--text-muted); font-size: 0.85rem; margin-top: 4px; }

.actions-row { display: flex; gap: 8px; flex-wrap: wrap; }

.form-row { display: flex; gap: 16px; flex-wrap: wrap; }
.form-row > div { flex: 1; min-width: 220px; }