Fix editor style for mobile and tablets

It closes #361.

Now it looks like this:
**Tablet**
![screen shot 2014-06-11 at 2 40 24 pm](https://cloud.githubusercontent.com/assets/230476/3245271/08ee9170-f171-11e3-9fe3-9056b38318b3.png)

**Mobile**
![screen shot 2014-06-11 at 3 00 40 pm](https://cloud.githubusercontent.com/assets/230476/3245275/15ec946c-f171-11e3-954f-5df78cb3fcf8.png)