Stuck on timeline animations for differing aspect ratios

I’m trying to create a timeline for my UI elements to reveal another menu. What I have right now is a bulletin board like design that would show off the lobbies currently open for joining.

Pressing the “View Collection” button would reveal the unlockable items you have collected/bought (with in game credits won from games). I’m trying to animate it in such a fashion that it would slide open to reveal the second menu:

The thing I’ve been kind of stuck at for the past couple of days is aspect ratios though, how something looks good in 16:9 ratio (what I usually test on), but for those playing on 16:10 or even 4:3, it looks wrong. The return button is now hidden behind the regular UI, which doesn’t go up far enough and could still show the lobbies

I’m currently using a timeline for the transition, with the server view being a stretched UI image on a Canvas set to “Scale with screen size”. I’m moving it using its Size Delta by moving/squeezing the bottom upwards while recording. But since that’s I guess based on pixels from the bottom or something, and not normalized from bottom to top, it doesn’t reach far enough.

I had been considering locking aspect ratio to 16:9, but I really don’t want to do that because it might look weird/smaller on devices that don’t use 16:9. Is there a better solution to making animations work with multiple aspect ratios? Is there something like normalized Anchored Positions or Size Delta?

Edit: The timeline in question, if it matters. The lighter panel is called BulletinView, and the darker background panel isn’t animated, but actually part of the entire background (hence it’s aptly named “Background”)