static header on all screens? HELP

Hi all, I’ve been trying to fix this for days but to no avail.

I want my header image to look the same on all screen resolutions. I’ve gone so far as to upload a background image as a header and then overlaying the logo as a separate layer on top. However when viewed on a 27″ iMac screen the header moves and looks weird. Is there any way I can make it look the same on ALL screens?

My site: http://capitalsoundstudios.com

It looks perfect on 13″-21″ screens but starts looking weird on anything bigger than those.

I’m at my wits end! PLEASE HELP

Thanks in advance