How to get theme variables purged by Tailwind in CSS selectors

[renadr]

Hello,
In Tailwind v4, I've created a theme, and I'm wondering how Tailwind could detect that some variables need to be removed in the final CSS when they are set under... let's say [data-theme="xx"].

Here is a minimal example:

@theme {
  --color-background-accent-primary: red;
  --color-background-accent-secondary: purple;
}

[data-theme="light"] {
  --color-background-accent-primary: blue;
  --color-background-accent-secondary: brown;
}

[data-theme="dark"] {
  --color-background-accent-primary: yellow;
  --color-background-accent-secondary: pink;
}

Now let's say in my code I only use a class that uses color-background-accent-primary. This variable will be in the generated CSS, but so will color-background-accent-secondary because it's defined in the [data-theme] selectors.

Now imagine I have more themes than these two, and also more variables. I'll end up with too many unused variables. Is there a better way to handle this?

[wongjn]

You could consider having sort of process that runs after Tailwind that detects the unused CSS variables and removes them as needed.