make .actionBar and actionBar.span size better with uncommon font-sizes

changed static sizes for actionBar to ems, because if a larger font-size is used, the text would (IDK i haven't tried it on all browsers) likely overflow out of the actionBar itself. I've attached an image:

![first](https://f.cloud.github.com/assets/4211302/2378138/62069890-a88b-11e3-8ed7-77c3a7982754.png)

and after the commit:

![after](https://f.cloud.github.com/assets/4211302/2378140/6a30b488-a88b-11e3-8e9a-e7346385742d.png)

Here, the actionBar is:
|
(TEXT)
|

(where '|' denotes one em)

So the text is properly aligned in the middle, with 1em margin (line-height to be precise) vertically, and 1em horizontally. I have also changed `body`'s padding to match this change.