Fixed element not working as expected

I’m struggling to get a div to work properly on mobile. I created filters for a CMS collection, and in the MOBILE view I need ‘Div Block 60’ to stay fixed at the bottom, however when I preview or export it doesn’t. FWIW the filter menu and component I’m referring is only revealed after tapping ‘Filters’. Here is the preview link. Any advice on how to get it to stay fixed at the bottom?