CSS fix for Modernizr csstransform3d false negative on some Linux Chromium releases

Using Chromium on Linux Mint, modernizr returns a csstransform3d false negative.
Pushy uses its JS fallaback while the browser correctly reads the CSS translate3d statements.
The result is that the menu contents remain hidden outside the page.

I added some CSS to reset translate3d values in case of a csstransform3d false negative.