Hoi members,
am working on a site ( www.bistrolafrontiere.com ) . Since a week I noticed that every time you go to another page the upper part of the screen is jumping up and the logo disapperas for a split second and then everything comes back.
Checked already all of the css code, but could not find any error.
May be it is not the CSS but another code ?
Can somebody have a critical eye on this problem?

I would be very thankfull.