Spectrum

http://bgrins.github.com/spectrum/

Thanks to the following places for good information as this plugin was being built:

• http://ansciath.tumblr.com/post/7347495869/css-aspect-ratio: Aspect ratio using CSS only
• https://github.com/DavidDurman/FlexiColorPicker for saturation/value gradient constants
• http://upload.wikimedia.org/wikipedia/commons/a/ad/HueScale.svg: For hue gradient constants