Menu missing when viewed on iphone 4 with ios7 safari

Hi,

The menu displays fine on chrome, firefox and ie on a pc when it is in the full or reduced sized versions. However, on my phone (iphone 4 with ios7 safari) the menu is not visible at all in either landscape or portrait. The Atomic web browser on my phone displays it correctly.

Any pointers on how to fix this would be great.

Thanks,

Paul