@henrywright that's because the commands changed recently.
./nodebb reset theme was valid at the time
I found a site microduino used nodebb.
how to do this?
I use Custom CSS or Custom Header,it's not work.
I think you need change theme templates, this file: node_modules/nodebb-theme-persona/templates/header.tpl
But you need realize, in this case updates to new versions may be more painfull.