refactor: update class names for consistency and improve styling

- Changed `flex-shrink-0` to `shrink-0` in multiple components for better consistency.
- Updated button and checkbox classes to use `rounded-sm` for a more uniform appearance.
- Adjusted backdrop blur classes for modals to `backdrop-blur-xs` for a subtler effect.
- Removed unused Tailwind CSS configuration file.

src/components/DateTimePicker.jsx

@@ -90,7 +90,7 @@ export default function DateTimePicker({
         </label>
       )}
       <div className="relative">
-        <Icon size={15} className="absolute left-3 top-1/2 -translate-y-1/2 text-th-text-s pointer-events-none z-[1]" />
+        <Icon size={15} className="absolute left-3 top-1/2 -translate-y-1/2 text-th-text-s pointer-events-none z-1" />
         <input
           ref={inputRef}
           type="text"