Menu bar at top of home page not "sticking"?

When I’m on the home page of my site and I scroll up, I noticed that the menu bar at the top isn’t “sticking” to the top of the page. That is, the menu doesn’t stay on the page…it scrolls off the top. I set “Sticky Navigation” to “On” in the header options, but it doesn’t work as expected.

I’m not sure if this is related, but I added a new logo to the site. The logo and site tag line disappear part way through scrolling up. I’d expect that they would scroll off the top of the page. but when I’ve scrolled to roughly halfway down the logo, both it and the tag line just disappear.

The site is at staging.travelstoriesandimages.com