Rudder

I just checked out the new display of Rules added in #4505, but have several display issues on my Firefox browser, as these screenshots show:

In particular, what is wrong:

• The size of the "highlight" box in the tree when I hover over an item is huge, and the + and - icons are miles apart from each other and the text
• Items in the two sections on the right are not displayed correctly (they don't have a box around them, they seem to drift from left to right, etc)
• The titles of the two boxes on the right are preceded by the question mark, that shuold come afterwards
• The " (Create a new Directive)" and " (Create a new Group)" links are far too big, and should be much more discrete (think half the current size, no bold, and in grey)