:root {
  --bg: #f4f6f9;
  --surface: #ffffff;
  --primary: #1d4ed8;
  --primary-light: #eff6ff;
  --text: #1e293b;
  --muted: #64748b;
  --border: #e2e8f0;
  --success: #16a34a;
  --warn: #d97706;
  --danger: #dc2626;
  --radius: 10px;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
}

.topbar {
  background: #0f172a;
  color: #fff;
  padding: 14px 24px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}
.topbar-brand h1 {
  margin: 0;
  font-size: 18px;
  font-weight: 600;
}
.topbar-brand .sub {
  font-size: 12px;
  color: #94a3b8;
}
.role-switcher {
  display: flex;
  align-items: center;
  gap: 10px;
  background: #1e293b;
  padding: 8px 14px;
  border-radius: 8px;
  border: 1px solid #334155;
}
.role-switcher label {
  font-size: 13px;
  color: #cbd5e1;
  white-space: nowrap;
}
.role-switcher select {
  background: #0f172a;
  color: #fff;
  border: 1px solid #475569;
  border-radius: 6px;
  padding: 6px 10px;
  font-size: 13px;
  max-width: 280px;
}

.scope-banner {
  background: var(--primary-light);
  border-bottom: 1px solid #bfdbfe;
  padding: 10px 24px;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  font-size: 13px;
}
.badge {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 999px;
  font-size: 12px;
  font-weight: 600;
}
.badge-blue { background: #dbeafe; color: #1e40af; }
.badge-green { background: #dcfce7; color: #166534; }
.badge-amber { background: #fef3c7; color: #92400e; }
.badge-red { background: #fee2e2; color: #991b1b; }

.nav-tabs {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 0 24px;
  display: flex;
  gap: 8px;
  overflow-x: auto;
}
.nav-tab {
  border: none;
  background: transparent;
  padding: 14px 18px;
  font-size: 14px;
  font-weight: 500;
  color: var(--muted);
  cursor: pointer;
  border-bottom: 2px solid transparent;
  white-space: nowrap;
}
.nav-tab.active {
  color: var(--primary);
  border-bottom-color: var(--primary);
  font-weight: 600;
}

.container {
  max-width: 1280px;
  margin: 20px auto;
  padding: 0 20px 40px;
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 20px;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.03);
}
.card-header {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  margin-bottom: 16px;
}
.card-title {
  margin: 0;
  font-size: 16px;
  font-weight: 600;
}

.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: center;
}
.control-group {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 13px;
}
.control-group input,
.control-group select {
  padding: 6px 10px;
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: 13px;
  background: #fff;
}
.control-group input[type="number"] {
  width: 78px;
}

.btn {
  padding: 7px 14px;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: #fff;
  color: var(--text);
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
}
.btn-primary {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}
.btn-primary:hover { background: #1e40af; }
.btn:hover { opacity: 0.92; }

.kpi-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(170px, 1fr));
  gap: 14px;
  margin-bottom: 20px;
}
.kpi-box {
  background: #f8fafc;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 14px;
}
.kpi-label {
  font-size: 12px;
  color: var(--muted);
}
.kpi-value {
  font-size: 24px;
  font-weight: 700;
  margin-top: 4px;
}
.kpi-sub {
  font-size: 12px;
  color: var(--muted);
  margin-top: 2px;
}

.table-wrap {
  overflow-x: auto;
}
table {
  width: 100%;
  border-collapse: collapse;
  font-size: 13px;
}
th, td {
  padding: 10px 12px;
  text-align: left;
  border-bottom: 1px solid var(--border);
  white-space: nowrap;
}
th {
  background: #f8fafc;
  font-weight: 600;
  color: #475569;
}
tr:hover td { background: #f8fafc; }

.bar-chart {
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.bar-row {
  display: grid;
  grid-template-columns: 76px 1fr 68px;
  align-items: center;
  gap: 10px;
  font-size: 13px;
}
.bar-track {
  background: #e2e8f0;
  border-radius: 999px;
  height: 14px;
  overflow: hidden;
}
.bar-fill {
  height: 100%;
  background: var(--primary);
  border-radius: 999px;
  transition: width 0.3s ease;
}
.bar-fill.weak { background: var(--danger); }
.bar-fill.good { background: var(--success); }

.student-layout {
  display: grid;
  grid-template-columns: 300px 1fr;
  gap: 20px;
}
@media (max-width: 860px) {
  .student-layout { grid-template-columns: 1fr; }
}
.student-list {
  max-height: 540px;
  overflow-y: auto;
  border: 1px solid var(--border);
  border-radius: 8px;
}
.student-item {
  padding: 10px 12px;
  border-bottom: 1px solid var(--border);
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 13px;
}
.student-item:hover, .student-item.active {
  background: var(--primary-light);
}

.hidden { display: none !important; }
.text-danger { color: var(--danger); font-weight: 600; }
.text-success { color: var(--success); font-weight: 600; }
.text-muted { color: var(--muted); }