The editor needs more CSS margin/passing so the entirety of the content is legible. As is now, the right most content can be hard to make out.
There's a question mark on the right-hand side that I couldn't see.
Also, when clicking the image button to add Media, the dialog open primarily outside of the viable area. I have to scroll upward to see it properly. It isn't centering properly.
This is on mobile via the Brave browser and I haven't tested in anything else.