googlechromelabs/postcss-jit-props

PostCSS JIT Props is a PostCSS plugin that automatically adds CSS custom properties to your stylesheet as they are used, eliminating the need to manually manage or purge unused variables. It's designed for developers working with large pools of CSS variables who want to streamline their workflow and ensure only used properties are included in the final output. The plugin supports CSS, JS, and JSON input formats, making it flexible for various development environments.