Working with RGBA colors in CSS3February 17, 2010
Drew McLellan’s article — Working with RGBA colour — on the 24 Ways website, describes how to use the opacity settings available in CSS3 to set transparency on various colored elements.
It seems you can only use these with RGB colors, not Hex values, so you’ll need to convert your hex values to RGB values if you want to take advantage of this attribute. Most graphics software will display both, so you shouldn’t need to get any other software. However, if you don’t want to open up your graphics software every time you need to grab the RGB values, there are some simple ‘on top’ tools that let you do this, such as ColorPix, which I mentioned on this blog back in March 2009.
That link to the article again: http://24ways.org/2009/working-with-rgba-colour
[Links last checked January 2010]