Strictly speaking the CSS 2.x specs recognize only 17 names: The same 16 color names as HTML, plus 'orange' rgb( 255, 165, 000).
Virtually all browsers recognize these color names now. But those color names will show up as errors in CSS 2.x validators. An error may appear as this:
Value Error : background-color lavender is not a color value : lavender lavender
Here's the big tip… A list of X11 colors organized by color groups. Much easier to find your desired color than in the other alphabetical and numerical lists I’ve seen.