Indent Children of Children in wp_list_pages

I am using wp_list_pages to display a list of a hierarchical custom post type. I understand basically that it creates a series of nested lists. I would like them to indent each child under its parent like an outline. The top level items are correctly positioned, as are the ones right under them, but level 3 and lower seem to be positioned at the same indent as level 2. Is there a simple CSS fix to resolve this issue?