Having trouble with style display:inline-block;

I am building a theme with a portfolio page here .
I am using custom post types to display the content in a grid format.

My problem is that when I tell the div that is containing the single custom post type to display: inline-block; it displays inline but stagers each div after that down about 10px as you go across from left to right.

Any Ideas on how to make them display actually inline, or maybe how to align them at the top of the containing div?