You can accomplish this in two ways.
If you give your Dropdown links a class (i have called it "Dropdown Link") And and padding on the left side of 40px. You can indent your Dropdown links to show the level. you would then need to add this class to each of your Dropdown Links.
The other way is to add a class to the Dropdown List (this is the element that holds all of your Dropdown Links).
You can then add padding to the left of the entire list and it will also give you soe indentation and show levels between links
Hope this helps!