Move .meta overflow to CSS, fix FF

Move the overflow properties for .meta from admin.js to style.css. Don't see a reason to have zepto handle this, as it doesn't change.

Also lets us set two hidden values, adding -moz-hidden-unscrollable, which although marked on [MDN](https://developer.mozilla.org/en-US/docs/Web/CSS/overflow) as "Non-standard intended mainly for internal use" it works. 

Anyway it makes Firefox not look like this:
![ffoverflow](https://f.cloud.github.com/assets/904055/1085440/676f897a-15d0-11e3-801b-7954c81fb338.png)