With CSS3 you can improve on efficiency as it saves lots of time and wasted space which would be taken up by images. Because it is an advanced version of CSS (Cascading Style Sheet) it also has it's downside with not working older browsers , but when you add up the pros and cons, CSS3 will always win with it's unlimited design capabilities and high performance.
You may be wondering what can I do differently with CSS3 which I can't do using the usual CSS. By using the present version you can create elements such as:
Box & Text Shadows
Drawing Border Images & Radius
I've compiled a collection of high quality CSS3 tutorials to help you learn these new techniques and bring your web development skills up to the present day standards.