Ctrl + - increases the resolution. You have to use it at least once to be able to use the next step. Rotating to landscape and back to portrait mode and the side elements will shrank to it’s minimum size. You can scale resolution further for more text space, but don’t do too much, because Ctrl + + does not work for no reason (resetting resolution is more complicated).
Or connect your mouse and drag&drop the sidebar as you can on desktop.
I provided all information to this topic here.