Scrollbar in pdf reader should be under the toolbar

I think that the scrollbar in pdf reader should be placed under the toolbar and not next to it, as in other browsers'.

It's not just a cosmetic issue. It's annoying when you open a single page pdf. At first, the scrollbar doesn't appear. When you press "zoom in" several times, once the page exceeds the length of the screen, the scroll bar suddenly appears. As a consequence, the toolbar unexpectedly moves to the left, so the mouse pointer is no longer on the zoom button, but on the "rotate" button.