How customize theme selector in tailwind-css

I want to start with the dark theme and later add the light colors by adding the light: selector. Is it possible to do something like this?

<div class="bg-black light:bg-red-300 py-6">

...

</div>

i read about this plugin but its not what i want exactly

You could consider using a Tailwind Plugin to register custom static variants. For example, if light is to be identified by some parent light class, you could do:

const plugin = require('tailwindcss/plugin')

module.exports = {
  // …
  plugins: [
    plugin(function({ addVariant }) {
      addVariant('light', '.light &');
    }),
  ],
};

This would then allow you to use class names like light:bg-red-300 which would generate CSS like:

.light .light\:bg-red-300 {
  …
}

Or if you wanted the opposite of dark: with its media query version, you could do:

const plugin = require('tailwindcss/plugin')

module.exports = {
  // …
  plugins: [
    plugin(function({ addVariant }) {
      addVariant('light', '@media (prefers-color-scheme: light)');
    }),
  ],
};

Which would generate:

@media (prefers-color-scheme: light) {
  .light\:bg-red-300 {
    …
  }
}

Though really, if you only want a variant that applies when "not dark", you could consider reworking the logic of your classes a little:

<div class="dark:bg-black bg-red-300 py-6">