The tabs in this demo are image-less tabs
with 4 different CSS3 enhancements:

1. Rounded Corners (border-radius)
2. Box Shadow (bottom of inactive tabs)
3. Transitions (the glow on hover)
4. Gradients (the active tab)

CSS Transitions work in Chrome, Safari 3.1+, Opera 10.5+, Firefox 4+, and IE10+

The basic idea and techniques presented here are taken from the tabs on the 2010 jQuery Conference site.