At present, only the configuration of css has been added to the settings, which may be convenient for users who are familiar with css. But this is not easy for everyone, so I will optimize it.

The font size may be set like other software in the future, the default unit is pt.

The problem that font-family cannot be loaded does not appear here. Maybe you need to switch notes to reload the outline window or restart joplin. If you still have problems with font-family, can you give me the details and screenshots.