The design for syntax highlighting is pretty clever, and makes that feature much more responsive than most in-browser editors. The current line is always black

The design for syntax highlighting is pretty clever, and makes that feature much more responsive than most in-browser editors. The current line is always black text on a light blue background... and then when you move the cursor to a new line, the highlighting is processed. I've implemented that kind of thing in the past, and making it perform well is always a ton of work. This approach is much more elegant and gets you 90% of the value. I like it!