As a reader, it would be incredibly more convenient if it just showed the things as margin notes (with a "read more" link if necessary to fit the space) instead

As a reader, it would be incredibly more convenient if it just showed the things as margin notes (with a "read more" link if necessary to fit the space) instead of all this whooshy business with buttons flying around and the page scrolling over when you click to expand and so on. It's all very distracting.