[REG 12.0.2 -> 13.0] Help mode resizes incorrectly

When I resize the Help mode, the contents are resized to roughly match the width of the view, but no matter what I do, it always shows a horizontal scrollbar and a I can move the contents left and right a little:

Instead, the help page should be resized to match the width of the view, so scrolling is not needed. Unless it's extremely narrow, of course.