Bug 1053708 - Make SMS main User Interface RTL-friendly

as much as possible I'm trying to use properties that know how to deal with RTL, only float does not have this yet.

Advantages of using such properties are:
* no risk of unexpected overrides (like in action_menu.css)
* easier maintainability

Inconvenients are:
* the implementation might change, especially for the prefixed ones. I think the risk is low though, and it will be easily caught if that happens.