Lead for MDL here. Glad you like the idea, spoiler :) Thanks for catching the low contrast issue with the dashboard navigation - is it the same as https://github.com/google/material-design-lite/issues/739?. If not, would you mind filing an issue on the repo and we'll try to get that fixed up soon?
https://github.com/google/material-design-lite/blob/master/C...
Alternatively, we can file a bug for you if you share details about the browser/os/device you were testing on.