:root {
  --primary: #06b6d4;
  --primary-hover: #0891b2;
  --primary-light: rgba(6, 182, 212, 0.12);
  --bg: #f8fafc;
  --card-bg: #ffffff;
  --border: #e2e8f0;
  --border-subtle: #f1f5f9;
  --text: #0f172a;
  --text-muted: #64748b;
  --radius: 12px;
  --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.07), 0 2px 4px -2px rgb(0 0 0 / 0.05);

  --color-tot: #10b981;
  --color-kha: #0284c7;
  --color-dat: #f59e0b;
  --color-chuadat: #ef4444;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b0f19;
    --card-bg: #111827;
    --border: #1f2937;
    --border-subtle: #1a2234;
    --text: #f9fafb;
    --text-muted: #9ca3af;
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
    --primary-light: rgba(6, 182, 212, 0.18);
  }
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

body {
  background-color: var(--bg);
  color: var(--text);
  line-height: 1.5;
  padding: 24px 16px;
}

.app-container {
  max-width: 1320px;
  margin: 0 auto;
}

/* Header */
.app-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
  margin-bottom: 24px;
}

.header-left {
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}

.btn-back {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 14px;
  background: var(--card-bg);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: var(--radius);
  text-decoration: none;
  font-size: 0.88rem;
  font-weight: 500;
  transition: all 0.2s;
}

.btn-back:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.header-icon {
  width: 48px;
  height: 48px;
  background: var(--primary-light);
  color: var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius);
}

.header-icon svg {
  width: 26px;
  height: 26px;
}

h1 {
  font-size: 1.65rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.subtitle {
  color: var(--text-muted);
  font-size: 0.88rem;
}

.header-actions {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

/* Buttons */
button {
  cursor: pointer;
  border: none;
  border-radius: 8px;
  font-size: 0.88rem;
  font-weight: 600;
  padding: 8px 16px;
  transition: all 0.2s ease;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
}

.btn-primary {
  background: #0ea5e9;
  background: linear-gradient(135deg, #06b6d4, #0284c7);
  color: #ffffff;
}

.btn-primary:hover {
  opacity: 0.92;
  box-shadow: 0 4px 12px rgba(6, 182, 212, 0.3);
}

.btn-secondary {
  background: var(--card-bg);
  color: var(--text);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background: rgba(148, 163, 184, 0.1);
  border-color: var(--text-muted);
}

.btn-backup {
  background: #0284c7;
  color: #ffffff;
}

.btn-backup:hover {
  background: #0369a1;
  box-shadow: 0 4px 12px rgba(2, 132, 199, 0.3);
}

.btn-restore {
  background: #475569;
  color: #ffffff;
}

.btn-restore:hover {
  background: #334155;
}

/* Toast */
.toast {
  position: fixed;
  bottom: 24px;
  right: 24px;
  background-color: #1e293b;
  color: #ffffff;
  padding: 10px 18px;
  border-radius: 8px;
  font-size: 13.5px;
  font-weight: 500;
  box-shadow: var(--shadow);
  opacity: 0;
  transform: translateY(20px);
  transition: all 0.3s ease;
  z-index: 9999;
  pointer-events: none;
}

.toast.show {
  opacity: 1;
  transform: translateY(0);
}

.btn-accent {
  background: #10b981;
  color: #ffffff;
}

.btn-accent:hover {
  background: #059669;
}

/* Config Bar */
.config-bar {
  display: flex;
  align-items: center;
  gap: 20px;
  background: var(--card-bg);
  border: 1px solid var(--border);
  padding: 14px 20px;
  border-radius: var(--radius);
  margin-bottom: 20px;
  flex-wrap: wrap;
  box-shadow: var(--shadow);
}

.config-item {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.9rem;
}

.config-item label {
  font-weight: 600;
  color: var(--text-muted);
}

select, input[type="text"], input[type="number"], textarea {
  background: var(--bg);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 6px 12px;
  font-size: 0.88rem;
  outline: none;
}

select:focus, input:focus, textarea:focus {
  border-color: var(--primary);
}

.stats-badge {
  margin-left: auto;
  font-size: 0.9rem;
  color: var(--text-muted);
}

/* Analytics Row */
.analytics-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 16px;
  margin-bottom: 24px;
}

.stat-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  text-align: center;
  box-shadow: var(--shadow);
}

.stat-num {
  font-size: 1.9rem;
  font-weight: 800;
  line-height: 1.2;
}

.stat-label {
  font-size: 0.82rem;
  color: var(--text-muted);
  margin-top: 4px;
  font-weight: 500;
}

.color-excellent { color: var(--color-tot); }
.color-good { color: var(--color-kha); }
.color-pass { color: var(--color-dat); }
.color-fail { color: var(--color-chuadat); }

/* Table Section */
.card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 20px;
  margin-bottom: 24px;
}

.table-toolbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
  gap: 12px;
  flex-wrap: wrap;
}

.search-box {
  display: flex;
  align-items: center;
  gap: 8px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 6px 12px;
  min-width: 280px;
}

.search-box svg {
  color: var(--text-muted);
}

.search-box input {
  background: transparent;
  border: none;
  padding: 0;
  width: 100%;
}

.table-responsive {
  overflow-x: auto;
}

.score-table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
  font-size: 0.9rem;
}

.score-table th, .score-table td {
  padding: 10px 12px;
  border-bottom: 1px solid var(--border);
}

.score-table th {
  background: rgba(148, 163, 184, 0.08);
  color: var(--text-muted);
  font-weight: 600;
  white-space: nowrap;
}

.score-table input {
  width: 60px;
  text-align: center;
  padding: 5px;
}

.student-name-input {
  width: 100% !important;
  min-width: 140px;
  text-align: left !important;
}

.rank-badge {
  display: inline-block;
  padding: 3px 8px;
  border-radius: 6px;
  font-size: 0.8rem;
  font-weight: 600;
  text-align: center;
}

.badge-tot { background: rgba(16, 185, 129, 0.15); color: #10b981; }
.badge-kha { background: rgba(2, 132, 199, 0.15); color: #0284c7; }
.badge-dat { background: rgba(245, 158, 11, 0.15); color: #d97706; }
.badge-chuadat { background: rgba(239, 68, 68, 0.15); color: #ef4444; }

.btn-delete-row {
  background: transparent;
  color: var(--text-muted);
  padding: 4px 8px;
  font-size: 1.1rem;
}

.btn-delete-row:hover {
  color: #ef4444;
}

/* Bulk Input Section */
.quick-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  cursor: pointer;
  user-select: none;
}

.quick-header h3 {
  font-size: 1rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 8px;
}

.quick-body {
  margin-top: 16px;
  display: block;
}

.quick-body.hidden {
  display: none;
}

.score-input.invalid-score {
  border-color: #ef4444 !important;
  background-color: rgba(239, 68, 68, 0.15) !important;
  color: #ef4444 !important;
  font-weight: 700;
  outline: 2px solid rgba(239, 68, 68, 0.3);
}

/* Drop Zone */
.drop-zone {
  border: 2px dashed var(--border);
  border-radius: var(--radius);
  padding: 32px 20px;
  text-align: center;
  background: var(--bg);
  cursor: pointer;
  transition: all 0.2s ease;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 12px;
  margin-bottom: 20px;
}

.drop-zone:hover, .drop-zone.dragover {
  border-color: var(--primary);
  background: var(--primary-light);
}

.drop-zone-icon {
  color: var(--primary);
}

.drop-zone-text {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.drop-zone-text strong {
  font-size: 0.95rem;
  color: var(--text);
}

.drop-zone-text span {
  font-size: 0.85rem;
  color: var(--text-muted);
}

.btn-choose-file {
  margin-top: 4px;
}

.file-info {
  margin-top: 8px;
  font-size: 0.85rem;
  padding: 6px 14px;
  border-radius: 6px;
  background: rgba(16, 185, 129, 0.15);
  color: #10b981;
  font-weight: 500;
}

.divider-text {
  display: flex;
  align-items: center;
  text-align: center;
  margin: 18px 0;
  color: var(--text-muted);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.05em;
}

.divider-text::before, .divider-text::after {
  content: '';
  flex: 1;
  border-bottom: 1px solid var(--border);
}

.divider-text span {
  padding: 0 12px;
}

/* Warning Toast */
.score-warning-toast {
  position: fixed;
  bottom: 24px;
  right: 24px;
  max-width: 420px;
  background: #ffffff;
  border-left: 4px solid #ef4444;
  border-top: 1px solid var(--border);
  border-right: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  border-radius: 8px;
  box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.2);
  padding: 14px 18px;
  display: flex;
  align-items: flex-start;
  gap: 12px;
  z-index: 9999;
  animation: slideUp 0.3s ease;
}

@media (prefers-color-scheme: dark) {
  .score-warning-toast {
    background: #1f2937;
  }
}

@keyframes slideUp {
  from {
    transform: translateY(20px);
    opacity: 0;
  }
  to {
    transform: translateY(0);
    opacity: 1;
  }
}

.score-warning-toast.hidden {
  display: none !important;
}

.warning-icon {
  font-size: 1.3rem;
  line-height: 1;
}

.warning-content {
  flex: 1;
  font-size: 0.88rem;
  line-height: 1.4;
}

.warning-content strong {
  display: block;
  color: #ef4444;
  margin-bottom: 2px;
}

.warning-content span {
  color: var(--text);
  word-break: break-word;
}

.warning-close {
  background: transparent;
  border: none;
  color: var(--text-muted);
  font-size: 1rem;
  padding: 0;
  cursor: pointer;
  line-height: 1;
}

.warning-close:hover {
  color: var(--text);
}

.quick-hint {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 10px;
}

#bulk-input {
  width: 100%;
  height: 120px;
  resize: vertical;
  margin-bottom: 12px;
  font-family: monospace;
  font-size: 0.85rem;
}

.app-footer {
  text-align: center;
  padding: 20px 0;
  color: var(--text-muted);
  font-size: 0.82rem;
}

/* Print styling */
@media print {
  body {
    background: #ffffff;
    color: #000000;
    padding: 0;
  }
  .header-actions, .btn-back, .quick-input-card, .table-toolbar, .btn-delete-row, .config-bar, .app-footer {
    display: none !important;
  }
  .card, .stat-card {
    border: none !important;
    box-shadow: none !important;
  }
  .score-table input {
    border: none;
    background: transparent;
  }
  .score-table th, .score-table td {
    border: 1px solid #ddd;
    color: #000;
  }
}