Web developers have long used jQuery to add new functionality to the browser and mask cross-browser incompatibilities. Now, eCSStender does the same for CSS, allowing you to mask cross-browser incompatibilities in CSS and prototype new CSS properties. Aaron Gustafson, developer of eCSStender, explains how eCSStender works and how you can build your own plugins. Check out the funky physics demo, and a demo showing how you can use standard W3C CSS properties without vendor prefixes on Safari and other browsers. In addition to his work on eCSStender, Aaron is Group Manager at WaSP and Principal at Easy Designs.