When scrolling PR changes horizontally, the UI is cut off on the left

[Neme12]

This can also be seen here in the pictures: #1699

Notice that there's about 8px horizontally on the left outside of the scroll viewer, which results in the content inside being cut off into whitespace when scrolling horizontally. This margin/padding should be inside the scroll viewer, not outside. That will also make the scrollbar full width.