Nested categories in sidebar

I want to build a sidebar with categories and sub-categories in it, so to say nested categories, but without a limitation on depth, so you can have as many sub categories of unlimited number of parent categories.

The thing and the problem is, that the sidebar is limited by width and when sub-category is present, it is nested with a bit of right padding(to illustrate it is a sub-category), so if you have enough depth in sub-categories it can cause problems, as there is limitation of width and therefor there won't be any space left to add right padding. I can't find a good solution for this, please share your thoughts with me, perhaps we could find a better way around.

Here's a picture to illustrate how it might look: