Changing Display on Collections Show Only

I am using the theme Emiglio and would like to make some changes to the Collections pages only. Right now, there are primary and secondary divs with the primary showing the Collection description and Contributors. Then on the right is the secondary div showing the actual collection items. What I want is to remove the contributor field (which whenever I do in the show.php file it breaks the site and it will not load) and to move the collection items to be directly under the description (which when I do this it does across the entire site). I only want this to occur when you are in the collections - not on the entire site. Any help would be very appreciated.

Ok, I figured out how to get the Contributors gone, but I still can’t figure out how I can eliminate the secondary div so the primary spans 100% only in collections show pages. When I edit the CSS, it does it site wide and I’m not sure how to limit it only to collections. Thank you!