How to make Category tree expand to right?

[draugz]

Hello! I'm using prestashop 1.6.

The question is how to create category menu which expands to right?

At the moment it expands to bottom, but I'd like to change it. Any advices in how to do that would be very useful.

I've searched the code, but haven't got any ideas so far. 

There is a simple example of how it should works in attachment.

[NemoPS]

You should be able to do it with css, like setting position: relative to the main elements, and position:absolute for the ul elements contained in it. Then just use left: 100% on it, so that it sticks to the right side, and top:0 so it aligns at the top