In the current design the sketch preview is pushed out of view if the corresponding code segment is long. This demands a lot of scrolling from the user, to edit the code and view the output.

Instead the layout should shift to a side-to-side, this would give the following benefits :
https://www.figma.com/file/s07vy3Z8JN7FvBIU50hJQs/Untitled?node-id=2%3A2