Margin between the window divider line and arrows disappears after switching Project Settings pages

Steps to reproduce:

1. Create a new project 
2. Open Project Settings > Tags and Layers
3. Observe the margin/gap between the arrows and the window divider line
4. Switch to UI Toolkit
5. Return to Tags and Layers
6. Observe the same area

Actual results: The margin/gap between the window divider line or scrollbar and the arrows is gone

Expected results: The margin/gap between the window divider line or scrollbar and the arrows should stay

Reproducible with versions: 6000.6.0a7, 6000.6.0b8, 6000.7.0a5

Not reproducible with versions: 6000.0.80f1, 6000.3.22f1, 6000.5.7f1, 6000.6.0a6

6000.6.0b8

Tested on (OS): MacBook Pro - Tahoe 26.6.1