The website has a unified page scroll feature that allows the menu, logo, navbar and footer to scroll with the thumbnails and any vertically scrolling image galleries. Additionally, you decide what scrolls and what does not scroll (e.g. the menu could scroll up but the logo could be fixed on the page and not move).
Open DESIGNS and then LAYOUT. Under WEBSITE CONTAINER turn on Unified Page Scrolling
Under LOGO, MENU, FOOTER and NAVBAR you can turn OFF Fixed Page Position to have those items scroll with the images or thumbnails.
IMPORTANT: if you want a gallery with images, videos and/or text to scroll vertically you can go under the Images and Video Overrides for that particular gallery (double click it in the media library) and select TRANSITION TYPE: vertical scroll