Two questions regarding the split view

Hi, in the “current doc & notes” split view, the “navigation” selection is gone for the pdf display. For a 2-col scientific pdf file, the lack of the 2-col “article mode” renders the pdf text so tiny that it would be unreadable. Using the zoom-in mode is not practical given the slow speed and serious lag to pan around. A related question: in the split view, is there a way to slide the boundary between the document and the notes. It would be great if we can shrink the notes so the pdf display can have a larger area of the estate.