Top menu issue

Hi there,
Could you take a look at this test site please.
http://www.feedermasters.co.uk/newsite/

I would like to make the top menu always visible on top and without the jumping effect after scroll.
I added this to the override.css
#gkHeaderNav { top: 0px !important }
gkHeaderNav #gkMainMenu { right: 0 !important}

The menu is on the left and overlapping the logo. any idea how to fix this?

Thanks very much
Atti

Could you please create a screenshot and mark problematic area on it?