style: clean up panel toggles style

Feature

Summary

consistent visual and code-wise appearance of the panel toggles

Does the result of the MR comply to our "definition of done"?

• Code reviewed

Tests

Are we able to test this new feature?

• Yes, you can test by following these steps: …

toggles are no q-items anymore (they are buttons now) and their style matches the prev/next buttons (size-wise).

Related Tickets

Related

Closes

#258 (closed)