Structure your Tailwind CSS classes for readability and maintainability. Instead of long chains of conditional classes with && operators, use object syntax with clear naming patterns. This improves code readability and makes maintenance significantly easier.

Instead of this:

className={cn(
  "h-9 w-9 p-0 font-normal",
  modifiers?.today && "bg-accent text-accent-foreground",
  modifiers?.selected && "bg-primary text-primary-foreground hover:bg-primary hover:text-primary-foreground",
  modifiers?.outside && "text-muted-foreground opacity-50 pointer-events-none",
  // many more conditions
)}

Do this instead:

className={cn({
  "h-9 w-9 p-0 font-normal": true,
  "bg-accent text-accent-foreground": modifiers?.today,
  "bg-primary text-primary-foreground hover:bg-primary hover:text-primary-foreground": modifiers?.selected,
  "text-muted-foreground opacity-50 pointer-events-none": modifiers?.outside,
  // cleaner and easier to read
})}

Additional recommendations:

These practices make your code more maintainable, easier to review, and better for internationalization.