Reference website: http://www.modernizr.com/
Example page: http://learning-html5.info/CSS3/CSS3_HSLAModernizr.html – view the source code. In this example, I am employing Hue, saturation, luminosity, and alpha similar to an example provided by the lynda.com training library. Older browsers will not support these CSS-3 enhancements, so an alternative is employed for these older browsers. For example, if IE 6 is the browser, an alternate view is provided (not a perfect match but a similar look). If Chrome or FireFox 4 is used, the actual HSLA features are displayed. Be sure to view the source code to confirm you understand how this tool is used to provide graceful degradation.
Result: Below is a screen capture of a page using IE8
Here is the same page viewed in Firefox 4.
Note the difference in how the individual divisions display.