2000 Honda Civic EX, what holds the side of the Under engine cover on the sides?

2000 Honda Civic EX, what holds the side of the Under engine cover on the sides?

Added (1). the back was scraping the ground, I took out a 6mm bolt from the front but the holes on the side are bigger. Am I missing some type of auto body snaps for the side?

Plastic rivets that were called "screvits" when I worked at a Mitsubishi dealer.