Resolve "Sidebar styling updates"

This is my first (real) MR! Feel free to be extra picky 😄

cc @jhampton @shampton

What does this MR do?

Fixes UI polish issues described in #54814 (closed).

What are the relevant issue numbers?

#54814 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• Security reports checked/validated by reviewer

Closes #54814 (closed)