:root {
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.06), 0 1px 3px rgba(0,0,0,0.1);
  --shadow-md: 0 2px 4px rgba(0,0,0,0.06), 0 4px 8px rgba(0,0,0,0.1);
  --shadow-lg: 0 4px 8px rgba(0,0,0,0.05), 0 10px 20px rgba(0,0,0,0.12);
  --shadow-xl: 0 8px 12px rgba(0,0,0,0.05), 0 20px 40px rgba(0,0,0,0.14);
}