/* Common variables and utilities */
:root {
  /* Animation durations */
  --transition-fast: 0.2s;
  --transition-normal: 0.3s;
  --transition-slow: 0.5s;

  /* Spacing */
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;

  /* Border radius */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;

  /* Z-index layers */
  --z-nav: 100;
  --z-sidebar: 90;
  --z-overlay: 80;
  --z-dropdown: 70;
  --z-content: 1;

  /* Shadows */
  --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 4px 8px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 8px 16px rgba(0, 0, 0, 0.1);

  /* Common transitions */
  --transition-all: all var(--transition-normal) ease;
  --transition-transform: transform var(--transition-normal) ease;
  --transition-opacity: opacity var(--transition-normal) ease;
}

/* Common animations */
@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes slideIn {
  from { transform: translateX(-100%); }
  to { transform: translateX(0); }
}

/* Utility classes */
.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

.fade-in {
  animation: fadeIn var(--transition-normal) ease;
}

.slide-in {
  animation: slideIn var(--transition-normal) ease;
}

/* Focus styles */
:focus-visible {
  outline: 2px solid var(--accent-color);
  outline-offset: 2px;
}