GUH i know im like. almost 2 days late to this X_X sorry

i havent messed around with the new themes at all yet so you might have to change some stuff around for that, as i'm still using the legacy themes, but you have to find the div/class name of whatever you're trying to put a border around first! you can use inspect element to do that, or i think spark has some posted on their profile.

if i wanted to put a border around the nav bar at the top like how i have it currently, i'd have to put this code https://pastebin.com/4jMny8iy to achieve that! (i was just using the asterisk as a marker for where to put the div/class name, which in this case would be "nav", so you can switch that out to whatever)

this also depends on what border you're using, so mess with the settings if it doesn't work for your border