Some people modify their userstyle.css to a similar effect (see this thread). However, I agree that a proper outline feature would be useful, and even think Typora handles it beautifully (by making it the secondary mode for the sidebar).
Some people modify their userstyle.css to a similar effect (see this thread). However, I agree that a proper outline feature would be useful, and even think Typora handles it beautifully (by making it the secondary mode for the sidebar).