Release version 136.0 of Firefox added the sidebar along with vertical tabs to the release build, which is great. However, there is a less than ideal interaction that occurs when the New Tab page is opened. Since the bookmarks toolbar is always visible on this page and pinned to the top of the screen, it causes the content at the top of the sidebar to move down to accomodate it, which is visually distracting and can hinder clicking at tabs via muscle memory. The following images show an example of the difference between the sidebar normally and in the New Tab page:
Notice how all of the tabs are moved down when the bookmarks toolbar is visible. One way to fix this might be to have the bookmarks toolbar start further to the right when the sidebar is enabled, so that it doesn't interfere with the vertical position of the elements on it. This would reduce the total width of the bookmarks toolbar in such cases.
