I have a very strange from when testing a website on Chrome.
The CSS is exactly the same but appears different. Plus tested on the same monitor.
Firefox

Chrome

You can see from the Chrome print screen the background image I am using for the knives/forks, its the background color of this image which changes.
The background image at http://www.cater-shawrecruitment.co.uk/webapp/templates/default/images/bgpage.jpg has an embedded colour profile, which different browsers will interpret differently. You’ll need to re-render the image without the embedded colour profile.
This is probably caused by using photoshop to simply ‘Save’ the JPG, rather than ‘Save for web’ing.