Yes, I have tried many things as well a long time ago. Nothing seemed to work. I believe it would work with flexbox, but that doesn’t work in Lovelace. I asked around on this community forum and came to a stop. I created a workaround back then for pages that were too short. I use gap-card (part of layout-card now) to add empty spaces at the bottom of my view, on the tabs that are shorter. It’s not ideal (especially with different devices that have different heights and conditional cards), but it get’s the job done till a better solution comes.
This was my post: 🔹 Card-mod - Add css styles to any lovelace card - #879 by ASNNetworks
And I got a response from TKBow: 🔹 Card-mod - Add css styles to any lovelace card - #901 by ASNNetworks
Maybe you can get this working with his answer. Though I have a feeling it’s not going to work as how you and I want it to work.
I hope HA will just create a core option to sticky cards to top and bottom of the page. This will solve all issues and remove the need to resort to hacky solutions.
Keep me updated! 