more improved. Emacs: Xah CSS Mode. You can now convert RGB hex color under cursor to HSL format (⁖
why should you convert? because, #rrggbb is one of the hack from history. HSL model isn't perfect, but is much more intuitive. You can change the hue, saturation, and lightness. For some explanation of HSL model and color samples, see: CSS3 HSL (Hue, Saturation, Lightness) Color Samples.