Hexadecimal color values are supported in all major browsers.
A hexadecimal color is specified with: #RRGGBB, where the RR (red), GG (green) and BB (blue) hexadecimal integers specify the components of the color. All values must be between 0 and FF.
For example, the #0000ff value is rendered as blue, because the blue component is set to its highest value (ff) and the others are set to 0.