CSS3 offers many new features that allow for effects previously requiring image editing or JavaScript programs. These include drop shadows, gradients, rounded corners, transparency, and animations. CSS3 selectors also allow targeting elements more precisely with less markup. Features like multiple backgrounds and flexible box layout reduce the need for divs. Browser support is improving, though graceful degradation is still needed. Tools like Selectivizr, CSS3 Pie and Modernizr help provide CSS3 support in older browsers.