PostCSS plugin to transform W3C CSS Color Module Level 4 rgb() new syntax to more compatible CSS (comma-separated rgb() or rgba()).

CSS Colors 4 syntax

rgb() = rgb( <percentage>{3} [ / <alpha-value> ]? ) |
        rgb( <number>{3} [ / <alpha-value> ]? )
<alpha-value> = <number> | <percentage>

CSS Colors 3 syntax (actual)

rgb() = rgb( <percentage>#{3}) |
        rgb( <integer>#{3})
rgba() = rgba( <percentage>#{3} , <alpha-value> ) |
         rgba( <integer>#{3} , <alpha-value> )
<alpha-value> = <number>

Example

.foo {
  /* Input example */
  color: rgb(250.5 255 255);
  background-image: linear-gradient(to bottom right, rgb(10% 11% 12% / 90%), rgb(23% 24% 25% / .5));
}

.foo {
  /* Output example */
  color: rgb(251, 255, 255);
  background-image: linear-gradient(to bottom right, rgba(10%, 11%, 12%, .9), rgba(23%, 24%, 25%, .5));
}

Usage

postcss([ require('postcss-color-rgb') ])

See PostCSS docs for examples for your environment.