Google Material design framework
leaf.kortes.se
leaf.kortes.se
A huge part of material is animations and behaviors and this doesn't have it. Simplest example is buttons. Go to http://www.google.com/design/ and over over the more button (or anything else that's clickable). You'll see it elevate a bit as if to come up and meet your cursor. Compare that to the buttons from the toolkit.
Feel free to contribute with your ideas and add some neat CSS3 animations to the framework.
Just like a religion telling people how, what, and when to eat the whole thing almost comes across as a compliance test. It is more absurd because user interface design is art. It is also a fundamental piece of branding: how magazines, web sites, and software communicate their differentiations to their user base.
As someone who pays a hell of a lot of attention to user interface design, and has run continuous A/B tests for years to millions of people, some of the elements are questionable. If you implement them you will confuse a sizable number of users. It looks good, but does not come across as one of those things like where Google tests multiple shades of a single color to see which works the best.
This CSS framework fails to replicate things like "ink" that fills an element with a tap color based on where in that element you tapped.
Or the way that a block of color slides across the input when you focus it and the placeholder slides up and scales down to turn into a label.
Material design is not a CSS theme, it requires many other interaction and animation aspects that the Polymer project is building out with their paper-* components.
In any case it does make way more sense than trying to replicate the design on your own and reinvent the wheel. Especially since there is nothing particularly creative in copying the design of someone else.
Having more choices is nicer.