Review bar obscures the bottom of the file tree
### Summary
The review bar slightly obscures the bottom of the file tree in some cases, making it difficult to interact with the last file in the list.
### Steps to reproduce
1) Add a review on a file in an MR
### What is the current *bug* behavior?

### What is the expected *correct* behavior?
The file tree should not be obscured under any circumstances.
### Output of checks
This bug happens on GitLab.com
issue