It’s a thin sheet of ice the Islanders tread on, and the smallest missteps can sink the ship no matter the intentions.

That was made clear last night at the Coliseum, where all of their hard work was buried under a few mistakes in a disheartening 4-1 loss to the Bruins.

“We’re not going to score a lot of goals with our lineup, you know?” said optimistic coach Jack Capuano. “Some nights we might, but we have to win those close games. But we competed hard.”

Yes, there was the slogan of the night: competed hard. It was the mighty Bruins, after all, now tied for second in the Eastern Conference with a 12-2-2 record. And they are the Islanders (8-11-1), the team that took its home record to a putrid 2-8-0 as it opens a six-game homestand — a death wish in this shortened season.

“When we’re playing in front of our fans in our building, you don’t want to have that type of record at home,” said goalie Evgeni Nabokov, who made 30 saves and held the team afloat when the game opened up in the third, the Islanders already down 3-1. “You just have to find a way to win. That’s the bottom line.”

The Islanders have been nothing if not inconsistent through the first 20 games of this 48-game season, showing why there is hope in the locker room, but sometimes not showing up at all. After an even first period, when the Islanders got Casey Cizikas’ second career goal and the Bruins got one from Adam McQuaid, the second period put the home team away.

Brad Marchand scored just 38 seconds into the period, then David Krejci got one less than five minutes later, making it 3-1. Then the Bruins went into a defensive turtle position, knowing they had all they needed to go home with another win.

By taking three second-period penalties, the Islanders’ momentum was stalled, and late in the third, Greg Campbell finished the scoring into an empty net.