Basic WordPress Theme Styling for Photography Portfolio

Hello, I need some extra development done on a site that is nearly complete, but needs some fine-tuning. The site is a basic grid-based photography portfolio with 4 columns of thumbnail images and rows that will keep on going down the page. We'll have one basic information page, and a small index icon that will return the viewer to the home page. When a small photo thumbnail is clicked - it will open the image in its own page and be sized appropriately with no sidebars or footer content or anything - it's a very clean modern design. I need some header styling / positioning, and some simple tweaks to the grid spacing of the thumbnail index and the inner page content. Very basic stuff for a good Wordpress / CSS developer. Please do not bid unless you are totally confident in your ability to do this project in a timely, professional manner so that we can be sure that you receive the five-star feedback you deserve. Thanks in advance. Further details about the site will be shared for interested bidders.