Quick CSS fix – displaying posts in a grid

I checked out the posts on this topic – but what I’m trying to do seems a bit more simple. I just want all of my archives and main blog page to display my titles and excerpts in a grid. So, I just edited the css to make them fit and floated them left. However, the second row is no longer flowing correctly. (it was originally!)

Would love some help here!

http://www.foodoffmyblock.com/blog/