Show color box even for modern CSS RGB, HSL, OKLCH values

[thernstig]

Example:

  --color-deep-navy: #0b1f50;
  --color-deep-navy-rgb: 11 31 80;

Shows as:

As using modern, space separate CSS RGB values becomes more and more used due to ability to use transparency with rgb() as e.g. background: rgb(255 255 255 / 80%), it would be nice to be able to define variables as:

  --color-deep-navy-rgb: 11 31 80;
  --color-deep-navy-rgb-80: 11 31 80 / 80%;

etc. to show a color wheel as well. oklch should also be supported as that is most likely the defacto standard going forward.

Other issues around modern CSS coloring:
#413
#314