The CSS Demo was inspired by the very popular CSS Zen Garden. The basic idea is to create varied looks for the same html file, using nothing but a css file. Currently my CSS demo has 3 different looks: 'Greebit', 'Karoo' and 'Undublu'. Each of these looks change the exact same html file, which you can see for yourself by viewing the source file.
While you are in the demo you can select the different looks by using the sub menu of the 'Change CSS' link. If you would like the javascript that allowed me to do this you can visit www.dynamicdrive.com.