Despite the editor/preview pane being fairly large, as seen in the picture not all of the content is displayed on the lefthand side (that which is below the base_url tag is not shown).
Scrolling manually allows one to see the rest of the content.
It’s a bit wonky and has also led to me creating errors in the textual content.
I’m using Chrome Version 75.0.3770.142 (Official Build) (64-bit) on OSX.