“featured image” not spanning whole screen

W need the depth of the featured image as it is, if not a little thinner – when we make the image itself thinner we get a really pixelated image showing in the scrolling homepage… but now no matter what we do the image won’t span across the whole screen as the template is designed – we managed to change the overall setting for featured images but it messed with our directory, so that won’t do – any other tips? Thank you!!

The page I need help with: [log in to see the link]