Modal's "Close" button is cut off/ not visible on mobile devices

[cade-exygy]

When testing the multiple listing images modal in DAHLIA on mobile devices, the modal's close button gets pushed down and is inaccessible.

Steps to reproduce:
On Mobile device:

• Go to a listing with Multiple Listing Images: https://dahlia-full.herokuapp.com/listings/a0W4U00000KnXGsUAN
• Open the + button modal

Tested on

• iOS Chrome and Safari
• Android Firefox

An important note: I am not seeing this issue when I go to storybook on mobile device: https://storybook.bloom.exygy.dev/?path=/story/blocks-image-card--four-images

Any advice would be appreciated!

QA Notes @cliu02 @cade-exygy:
Do you mind closing this ticket whenever you get the chance to verify that uptaking the new UI-C version resolves this issue?

[ColinBuyck]

We have experience fixing this sort of mobile issue! Check out this PR from Emily for more context. @sarahlazarich I believe we could use that PR as a model to fix this and it would be pretty straightforward.