edit widget php

I have an interesting widget issue. I am trying to make two widgets half of the size and next to each other. Like the categories widget and the blogroll widget on this site:
http://www.dailybitesblog.com/

I can’t do this in the css because all of the widgets have the same id, so i’m thinking I need to edit the php function for each of the widgets, but I don’t know where to do this.