embiggen category icon click targets (bug 1058512)

Before:

![](http://f.cl.ly/items/3V0x0m1g1w190U0m1N09/Image%202014-09-25%20at%203.48.31%20PM.png)

After:

![](http://f.cl.ly/items/3z3V1E2D3j3r1C373U1L/Image%202014-09-25%20at%203.49.34%20PM.png)