Myth is an open source preprocessor that allows you to use some of the new/proposed/experimental CSS specifications being developed by W3C’s CSS working group. It does this by converting your code to CSS that’s understood by today’s web browsers.
Here’s some of the CSS specs which are still in development, that Myth can implement today:
If you’re interested in this subject, I wrote a Myth tutorial for SitePoint to help developers explore and get started with this unique preprocessor.
The tutorial includes a demo page (and source code) that I developed using Myth.
Getting Started with Myth: the Preprocessor of the Future (sitepoint.com)