You can easily do this by adding the following code to your code:

className={md:${window.scrollY > 0 ? "bg-slate-50" : "bg-transparent"}}

This is what Tailwind does. Otherwise you can write custom CSS yourself.

Please note, please make sure to include the required variants in your tailwind.config.js if not already enabled:

module.exports = {
      variants: {
        backgroundColor: ['responsive', 'hover', 'focus'],
        // ... other configurations
      },
}

${window.scrollY > 0 ? "max-md:bg-slate-50" : ""}