RTL CSS improvements

Take a look at the image below to see the 'before' and 'after' screenshots. This patch fixes a bug where the RTL layouts do not have the same sidebar separator as the LTR layouts. I noticed this during the creation of my sidebar resize patch.

![poc](https://f.cloud.github.com/assets/1993262/1968710/f7352596-82e6-11e3-910a-52c8e519d8c3.png)