Thumbnails problems - Amsterdam template

Hi guys!
I would like to reduce the space between my thumbnails (233x350px) in Amsterdam template, but when I do it the navigation content (pages) is no longer aligned to the block of thumbnails (it's a little bit of the left). In addition, the block of thumbnails seems to be no longer centered to the browser page.

I only changed to "7px" the values in this part of the code:
.project_thumb {
float: left;
margin: 0 7px 7px 0;
position: relative;
}

The original values were:
.project_thumb {
float: left;
margin: 0 30px 20px 0;
position: relative;
}

Thank you very much for your help!