I did that initially:
#cck27r_label_subject {width: 200px;}
The labels are in a search form with multiple fields (multi-selects, generic search, single select). When you pick different items in the fields, and then press the search button, then the label names change with the different search results. So the form could look pretty with the correct CSS and then look ugly with the search results below it. The number in the field kept changing: #cck<number>r_label... cck6r, cck1r, cck4r, cck3r. I didn't know all the possible div label ids with different numbers that would result from the search criteria. So I stopped using this CSS styling method.