This may be useful or not to test whether a given string is a valid (more or less) html color value. It matches color values such as:
#123 - short hex color value
#123456 - hex color value
rgb(255,255,0) - rgb color value
rgba(255,255,0,1.0) - rgba color value
hsl(360,100%,100%) - hsl color value
hsla(360,100%,100%,0.5334) - hsla color value
Regex allows whitespaces between i.e. rgb and (, also between numbers and commas, but not in value like 55% between number and percentage. To change this behaviour simply remove \s*? from appriopriate places.