Shrink the search label in Manage User page

Before:
![screen shot 2014-11-01 at 10 51 54 pm](https://cloud.githubusercontent.com/assets/1354889/4963367/1ecae5a8-670e-11e4-9d22-141327b2e334.png)

After:
![screen shot 2014-11-01 at 10 52 06 pm](https://cloud.githubusercontent.com/assets/1354889/4963366/1c0a9408-670e-11e4-9672-107c2ae7a264.png)


Fixes #17815
For my education as I've always been told not to use `!important` (or at least to avoid it as much as possible), why do we need it here and is there no alternative to it ?