Clean theme compatibility improvements

* Line height set according to WCAG 2.0 recommendations
* Font size inheritance problem solved - fixes 48 labels (buttons inputs and etc did not inherit the value properly)
* Tested on Clean and Standard theme

# Problem:

![before](https://cloud.githubusercontent.com/assets/6906827/2959364/1be1e276-dab2-11e3-85ac-308d53519df7.PNG)

# Solution:
![solution](https://cloud.githubusercontent.com/assets/6906827/2959359/0c31078a-dab2-11e3-96b1-85ccd590ce02.PNG)