With CSS 3 you can easily create some awesome effects, like nice borders, opacity-effects, roundings or beautiful text effects. How you could easily use it to improve your site i want to show in this tutorial series. In the first two tutorials we start with some basics and then move on to some more sophisticated things.
Remember CSS3 is not supported in all browsers, above all on old Internet Explorer Versions (prior IE 9) most effects will not work, but for the good part most modern mobile browser nd Chrome Safari (both Webkit) and Mozilla offer full support for CSS 3. A very nice overview table about CSS Browser support, you can find at http://www.normansblog.de/demos/browser-support-checklist-css3/.