HTML5 and CSS3 mobile website

Hi

I have built a HTML5 website and have just finished a mobile version of the website and looks ok in iphone 4s portrait view but when in landscape view the menu is miles down the page

see link below

http://www.irhwebsites.co.uk/mobile/portfolio.html

I am not 100% sure on how to get it looking ok when in landscape view

Any ideas would be great, I have tried moving the menu down using percentages and that is how I got it looking ok in portrait view

I got the following style for the thumbs li



Thank you

Ian