Get GoTTY running in your browser.
Go to Source, select gotty.js and pause.
Within the Scope section, within Local variables, there's a this
.
Go to this.profs_
, right-click and save as global variable.
Go over the console and run something like:
temp1.set('font-family', 'Inconsolata-g for Powerline')
temp1.set('background-color', '#202020')
The settings seem to go into LocalStorage and persist across sessions.