Place this code sample in your playground:
<color green>text</color> <color blue/lightgrey>text</color> <color #FF0000>text</color> <color /#FFff00>text</color> <color rgb(80%,0%,0%)/rgb(100%,80%,100%)>text</color> <color hsl(120,100%,30%)/hsl(180,50%,90%)>text</color>
and you will see something like this:
This plugin supports the X11 color names, hex triples (like #123 or #123456 for rgb), hex quadruples (#1234 or #12345678 for rgba), rgb, rgba, hsl, and hsla color specifications. This plugin does not try hard to catch syntax errors in your color specifications, however. If you use these specifications wrong, you may simply notice that they won't work. Beware that not all color specifications work on all browsers. Check Can I Use if in doubt.
Christopher Smith seems to have left the plugin unmaintained. User leeyc0 provided hosting of the plugin on github, but has no time to maintain it either. Harald Hanche-Olsen took over in October 2018. The plugin is considered fairly stable, though, and the new maintainer does not foresee a very active maintenance schedule.
Solidpost Note
The Plugin is still experimental here