category page width

Having a strange issue with one of my category pages.
When clicking on the link for the category page (electronicsmain.com/category/weekly-mobile-tech-news/)
the page is about half the width of the entire site. If I choose a single post, it’s fine. Where can I find a place to reconfigure the (for lack of a better word – landing/main page) to make it as it was?

Don’t know how or when this happened, anyone have a suggestion?
Thanks for your help