Improve mobile review ui (#31091) (#31136)

Improve mobile review ui (#31091) (#31136)

Backport #31091 by @silverwind

Fixes: https://github.com/go-gitea/gitea/issues/31071
Not perfect but much better than before.

Before: Overflows, sticky not working, filename unreadable:

<img width="506" alt="Screenshot 2024-05-27 at 02 02 40"
src="https://github.com/go-gitea/gitea/assets/115237/a06b1edf-dece-4402-98c2-68670fca265f">

After:
<img width="457" alt="Screenshot 2024-05-27 at 01 59 06"
src="https://github.com/go-gitea/gitea/assets/115237/2a282c96-e719-4554-b418-81963ae6269c">

Co-authored-by: silverwind <me@silverwind.io>