May 26
'===' should work like '---'
When you type '---' at the start of a line you get a single line "level" across the note (a separator). I'm suggesting that when you type '===' at the start of a line, you should get a double-line "level" across the note. This would further emphasize the start of new section of the note.
Pending
Thanks for sharing this, it's an interesting idea! Like others mentioned, it's not in the markdown standard, but NotePlan has a couple of things which are not included. I can imagine adding this as an option to the theme files.