Thank you so much for your suggestions @David and @webdeersign
I’ll give those a try. Here’s what’s making my situation more complicated (and I guess it has to do with going outside of Foundry).
On my website: http://markuswernig.net/ I am creating a grid using Doobox’s GRID, which gives me full control over gutter spacing (which Foundry’s Grid doesn’t). Then I am using Doobox’s VIDEO PLUS to launch videos in a really nice and unique lightbox effect (they are also the only ones - as far as I know - who allow me to use actual VIMEO embed code in their video lightbox stack, which gives me much more control.)
So any hover stack would have to go inside the VIDEO PLUS stack. So far all hover stacks that I tried threw the grid out of whack.
Maybe it has to do with Doobox’s stacks, maybe it’s the combination of their stacks with Foundry. - I’ll have to do more experimenting.