Sticky Menu, logo disappearing

Hi,

I changed my menu to the centered logo setup, and it’s sticky. But when I scroll down, the logo disappears (instead of shrinking to fit), and instead there’s a big ugly white space above the menu. Is this how it’s supposed to work?

Screenshot: https://imgur.com/a/Buzx6 (My site is under construction right now, so please let me know if you need to get into the back end to see what’s going on.

Thank you.

Ticket