CSS3 offers a whole lot of interesting functionality that you didn't know about but will really help you make your sites into something special. Just be conscious of browser compatibility issues -- some of these aren't available on older browsers.
This section contains helpful links to other content. It isn't required, so consider it supplemental for if you need to dive deeper into something
:afterPseudo-Elements in CSS from Smashing Magazine
From the creators of The Odin Project...