This section of the site allows you to change the skin of this site:

There are a variety of looks available in the pull-down menu above. Choose the look you want and click Change Skin and your choice will be saved for your session on this site. New skins will be added to the site over time. Have a look at CSS Zen Garden to get an idea of what could be done with CSS based design.

Implementation:

This idea was inspired by CSS Zen Garden. Each page has the same HTML but a different style sheet. The skin changer only changes the style sheet and sets it with PHP's Session Handling Functions. The index.php checks if you've set a skin otherwise it defaults to the Tabs Clean look. Have a look at skin_chooser.php and index.php if you want to see the code.