css should hook into the new html5 elements just fine. Can we see the full css and the full html, both for the working example, and for the non-working? I’m betting it’s something which another pair of eyes will pick up on.
ok, Chrome’s developers tools has slightly different features that FireBug so I was able to see that changing <div id=“menu”> to <nav> makes specificity of the responsive library I’m using http://purecss.io/ change.