Read this article and answer this question After a tough road win over the Bolts, the Steelers returned home to take on the Cardinals.  The Cards would strike first in the first quarter when Carson Palmer found Michael Floyd on a 3-yard pass for a 7-0 lead for the only score of the period.  The Steelers got on the board in the 2nd quarter when Chris Boswell nailed a 47-yard field goal for a 7-3 game before the Cards moved ahead by a TD after Chandler Catanzaro kicked a field goal of his own from 31 yards out for a 10-3 game at halftime.  After the break, in the third quarter it was all Steelers as Boswell kicked another field goal.  This was from 48 yards out to get the Steelers within 4, 10-6.  3rd-string QB Landry Jones replaced Michael Vick for the rest of the game and threw his first career TD to Martavis Bryant from 8 yards out (with a failed 2-point conversion) and a 12-10 lead.  Boswell hit a field goal from 51 yards out to send the Steelers up by 5, 15-10.  In the fourth quarter, the Cards narrowed the Steelers' lead as Catanzaro kicked a 39-yard field goal for a 15-13 game.  The Steelers increased their lead when Boswell made a 28-yard field goal for an 18-13 game.  Finally, they were able to seal the game when Jones found Bryant on an 88-yard pass for the final score of 25-13. With the win, the Steelers improved to 4-2.  The defense also continued their stellar outings in sacks and takeaways such as sacking Palmer once, picking him off twice, and recovering a fumble.
How many points were the Cardinals winning by at halftime?
7