My subcategories menu does not indent child categories

I have a left column that displays like this (amrita-edizioni.com) Main Category - >Subcat 1- >Subcat 1.1 >Subcat 1.2 >Subcat 2 I need to indent Subcat 1.1 and Subcat 1.2, now it displays all at same margin-left, and it's very hard to understand that Subcat 1.1 and Subcat 1.2 are only under Subcat1. I hope I have been clear enough. Thanks a lot for help!

Hello 

paste this CSS code snippet to your theme's css styles:

.categories_block_left.block li li {padding-left:15px;}

the effect will be like: