Answer based on context:

The Steelers started their season on the road against the Browns.  They scored first in the first quarter when Tyler Matakevich blocked a punt and Anthony Chickillo recovered it for a touchdown for a 7-0 lead.  Later on in the quarter, DeShone Kizer ran for a 1-yard touchdown to tie the game up 7-7.  In the second quarter, the Steelers retook the lead when Ben Roethlisberger found Jesse James on a 4-yard pass to make it 14-7 at halftime.  After the break, the Browns came closer in the third quarter when Zane Gonzalez nailed a 24-yard field goal to make it 14-10.  Though the Steelers moved ahead by double digits when Roethlisberger found James again on a 2-yard pass to make it 21-10.  The Browns tried to rally in the fourth quarter but could only come up with 8 when Kizer found Corey Coleman on a 3-yard pass with a 2-point conversion tacked on to make the final score 21-18. With their 5th straight win over the Browns, the Steelers started their season 1-0.  It also took the team's regular season winning streak to 8 straight while taking their winning streak against division rivals to 5 straight.

How many points did Steelers win by?
3