:root {
  --primary-color: #4F46E5; /* A modern indigo */
  --primary-hover: #4338ca;
  --bg-color: #f3f4f6;
  --text-dark: #1f2937;
  --text-muted: #6b7280;
}

body {
  background-color: var(--bg-color);
  font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  color: var(--text-dark);
}

/* Navbar Styling */
.navbar {
  background-color: #111827 !important;
  box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.navbar-brand {
  font-weight: 700;
  letter-spacing: 0.5px;
}

/* Card Improvements */
.card {
  border: none;
  border-radius: 12px;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  overflow: hidden;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 10px 15px rgba(0, 0, 0, 0.1);
}

/* Buttons and Badges */
.btn-primary {
  background-color: var(--primary-color);
  border-color: var(--primary-color);
}

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

.badge {
  font-size: 0.85rem;
  padding: 0.4em 0.6em;
  border-radius: 6px;
}

/* Media Players */
video, audio {
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
  background: #000;
}

.active-lesson {
    border-left: 4px solid var(--primary-color) !important;
}

.bg-black {
    background-color: #000;
}

.list-group-item-action:hover {
    background-color: #f8f9fa;
}