Hi Alexi, take a look at this demo:
Site: Demo kit
page: Sticky Navigation
See if that helps to show how to set this up If you need help with your site, update your post with some more information so we can help you faster? Things like your read-only link, and screenshots of the elements in question really speed things up.
Posting guidelines can be found here: Posting Guidelines for the Design Help Category
Thanks in advance!