:root {
  --primary-color: #2563eb;
  --secondary-color: #7c3aed;
  --success-color: #059669;
  --danger-color: #dc2626;
  --bg-color: #f8fafc;
  --card-bg: #ffffff;
  --text-primary: #1e293b;
  --text-secondary: #64748b;
  --border-color: #e2e8f0;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.15);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  min-height: 100vh;
  color: var(--text-primary);
  padding: 2rem;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
}

header {
  background: var(--card-bg);
  padding: 2rem;
  border-radius: 1rem;
  box-shadow: var(--shadow-lg);
  margin-bottom: 2rem;
}

h1 {
  font-size: 2.5rem;
  color: var(--primary-color);
  margin-bottom: 0.5rem;
}

.subtitle {
  color: var(--text-secondary);
  font-size: 1.1rem;
}

.admin-controls {
  background: var(--card-bg);
  padding: 1.5rem;
  border-radius: 1rem;
  box-shadow: var(--shadow);
  margin-bottom: 2rem;
}

.btn-group {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

.autosave-status {
  align-self: center;
  font-size: 0.9rem;
  color: var(--text-secondary);
  padding: 0.35rem 0.6rem;
  border-radius: 0.4rem;
  background: rgba(15, 23, 42, 0.06);
  border: 1px solid rgba(15, 23, 42, 0.08);
}

.autosave-status[data-state="saving"] {
  color: #0f172a;
  background: #eef2ff;
  border-color: rgba(99, 102, 241, 0.3);
}

.autosave-status[data-state="saved"] {
  color: #065f46;
  background: #ecfdf3;
  border-color: rgba(16, 185, 129, 0.35);
}

.autosave-status[data-state="error"] {
  color: #991b1b;
  background: #fef2f2;
  border-color: rgba(239, 68, 68, 0.35);
}

button {
  padding: 0.75rem 1.5rem;
  border: none;
  border-radius: 0.5rem;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

button:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

.btn-primary {
  background: var(--primary-color);
  color: white;
}

.btn-primary:hover {
  background: #1d4ed8;
}

.btn-success {
  background: var(--success-color);
  color: white;
}

.btn-success:hover {
  background: #047857;
}

.btn-danger {
  background: var(--danger-color);
  color: white;
}

.btn-danger:hover {
  background: #b91c1c;
}

.btn-secondary {
  background: var(--text-secondary);
  color: white;
}

.btn-secondary:hover {
  background: #475569;
}

.subjects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

.subject-card {
  background: var(--card-bg);
  border-radius: 1rem;
  padding: 1.5rem;
  box-shadow: var(--shadow-lg);
  transition: all 0.3s ease;
  border: 2px solid transparent;
}

.subject-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.2);
}

.subject-card.dragging {
  opacity: 0.5;
  cursor: move;
}

.subject-card.drag-over {
  border-color: var(--primary-color);
  background: #eff6ff;
}

.subject-header {
  display: flex;
  justify-content: space-between;
  align-items: start;
  margin-bottom: 1rem;
  border-bottom: 2px solid var(--border-color);
  padding-bottom: 1rem;
}

.subject-title {
  font-size: 1.5rem;
  color: var(--primary-color);
  font-weight: 700;
}

.drag-handle {
  cursor: move;
  color: var(--text-secondary);
  font-size: 1.5rem;
  padding: 0.25rem;
}

.subject-description {
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
  line-height: 1.6;
}

.simulations-list {
  list-style: none;
}

.simulation-item {
  background: var(--bg-color);
  padding: 1rem;
  border-radius: 0.5rem;
  margin-bottom: 0.75rem;
  transition: all 0.3s ease;
  border-left: 4px solid var(--secondary-color);
}

.simulation-drag-row {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.simulation-drag-handle {
  cursor: grab;
  user-select: none;
  font-size: 1.1rem;
  color: var(--text-secondary);
  padding: 0.15rem 0.35rem;
  border-radius: 0.35rem;
}

.simulation-drag-handle:active {
  cursor: grabbing;
}

.simulation-item.drag-over-sim {
  background: #e8f0ff;
  border-left-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.2);
}

.simulation-item:hover {
  background: #e0e7ff;
  transform: translateX(5px);
}

.simulation-link {
  text-decoration: none;
  color: var(--text-primary);
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.simulation-link:hover {
  color: var(--secondary-color);
}

.simulation-desc {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-top: 0.25rem;
}

.subject-actions {
  display: flex;
  gap: 0.5rem;
  margin-top: 1rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border-color);
}

.btn-small {
  padding: 0.5rem 1rem;
  font-size: 0.875rem;
}

/* Modal Styles */
.modal {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.7);
  z-index: 1000;
  align-items: center;
  justify-content: center;
}

.modal.active {
  display: flex;
}

.modal-content {
  background: var(--card-bg);
  padding: 2rem;
  border-radius: 1rem;
  max-width: 500px;
  width: 90%;
  max-height: 90vh;
  overflow-y: auto;
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.5rem;
}

.modal-title {
  font-size: 1.5rem;
  color: var(--primary-color);
}

.close-btn {
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--text-secondary);
  padding: 0;
  width: 2rem;
  height: 2rem;
}

.close-btn:hover {
  color: var(--danger-color);
  transform: none;
  box-shadow: none;
}

.form-group {
  margin-bottom: 1.5rem;
}

.form-group label {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: 600;
  color: var(--text-primary);
}

.form-group input,
.form-group textarea,
.form-group select {
  width: 100%;
  padding: 0.75rem;
  border: 2px solid var(--border-color);
  border-radius: 0.5rem;
  font-size: 1rem;
  font-family: inherit;
  transition: border-color 0.3s ease;
  background-color: white;
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
  outline: none;
  border-color: var(--primary-color);
}

.form-group select {
  cursor: pointer;
}

.form-group small {
  display: block;
  margin-top: 0.5rem;
  font-size: 0.875rem;
}

.form-group textarea {
  min-height: 100px;
  resize: vertical;
}

.modal-actions {
  display: flex;
  gap: 1rem;
  justify-content: flex-end;
}

/* Empty State */
.empty-state {
  text-align: center;
  padding: 4rem 2rem;
  background: var(--card-bg);
  border-radius: 1rem;
  box-shadow: var(--shadow);
}

.empty-state h2 {
  color: var(--text-secondary);
  margin-bottom: 1rem;
}

/* Responsive */
@media (max-width: 768px) {
  body {
    padding: 1rem;
  }

  h1 {
    font-size: 2rem;
  }

  .subjects-grid {
    grid-template-columns: 1fr;
  }

  .btn-group {
    flex-direction: column;
  }

  button {
    width: 100%;
  }
}

/* Animations */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.subject-card {
  animation: fadeIn 0.5s ease;
}