As an Ameritard, I know fuck all about soccer so this is probably an obvious take. However, I watched this game because Croatia appears to be a team of actual Croatians and not a team cobbled together from other continents. So as a new observer with very little soccer knowledge, a couple of things jumped out at me. Correct me if I'm wrong.
First, Croatia seemed to me to know that they couldn't match Brazil for speed so they really dialed up the ball control and positioning, essentially relying on a game of keep away. They also looked like they couldn't get a decent shot on goal past Brazil's defenders and so 10 minutes in to the game it seemed obvious to me that they were aiming for a 0-0 game to be decided in penalties.
Second, they knew they had the better goalkeeper and that in penalties the disadvantage the team had in speed and defense, wouldn't matter. They knew their advantage was pretty much only in the penalty kick part of the game, so they played their game masterfully to get it to a stage where they could play to their strength and force it to that point.
How far off am I?