Miami (CNN)This was Donald Trump's moment of Zen.
A chastened Florida Sen. Marco Rubio got back to basics. Texas Sen. Ted Cruz focused on his pitch to become the sole Trump alternative. And Ohio Gov. John Kasich kept up his routine of staying above the fray.
All of which allowed Trump to drop his usual insults and try on a new hat: party unifier.
It was the final debate before Tuesday's winner-take-all elections in Florida and Ohio and delegate-rich contests in Illinois, North Carolina and Missouri.
Here are five takeaways.
1. The "civil" debate
No name-calling. No personal insults about "hand" size. No moderator-bashing.
What came over these guys?
"So far I cannot believe how civil it's been up here," Trump said early on, when he noticed no one was jumping on him.
Make no mistake: Trump benefitted the most from the relative niceness on stage. Nothing that happened Thursday night will dent his status as the Republican front-runner -- particularly as the delegate math grows increasingly daunting for his rivals.
That the candidates were straining to play nice was especially clear when Trump and his rivals were asked about the violence at Trump's rallies.
Trump said he didn't condone it. And while his opponents spoke out against violence in general, they didn't blame Trump for creating a culture that encourages it -- instead trying to tap into the anger and frustration within the GOP themselves.
"How many of you all feel disrespected by Washington?" Cruz said, looking to the audience to help explain the anger many Republicans -- including Trump supporters -- are feeling. "Washington isn't listening to the people."
2. There was substance, but was it substantive?
Yes, in dropping their personal attacks, the candidates spent more time addressing policy issues like the debt, trade, immigration and education.
But even though CNN's moderators pressed for specifics, many of the candidates' answers offered only a brief, often broad-brush mention of how they'd attempt to solve the problems before them.
Asked about torture techniques like waterboarding, Trump said: "We have to obey the laws, but we have to expand those laws" -- without explaining how he'd like to see them expanded.
On how he'd shore up Social Security, Trump seemed to suggest he'd pull the U.S. military support in Germany, Japan and South Korea to pay for the program.
Cruz promised to end Common Core, even though it's being implemented by individual states, not the federal government.
"If I am elected president, in the first days as president, I will direct the Department of Education that Common Core ends that day," he said.
Cruz, however, was the most effective in pressing Trump for more details, particularly on addressing the deficit.
The Texas senator said he'd eliminate five major agencies, accounting for 25 programs, and cut $500 billion total.
"You've got to be willing to take on the lobbyists, which means not just some fanciful waste, fraud and abuse but specifying, 'These are the programs I would eliminate,'" Cruz said.
3. Trump holds to his line on Islam
Rubio's attack on Trump's comment that Islam hates Americans stood out: It was pitch-perfect for a general election.
Pressed about his remark Wednesday night in an interview with CNN's Anderson Cooper, Trump at the debate decried political correctness -- teeing up Rubio for one of the most memorable lines of the night.
"I'm not interested in being politically correct -- I'm interested in being correct," he said, continuing that the U.S. depends on the support of Muslims to fight ISIS and that there are loyal American soldiers who are adherents of Islam.
Many Republican primary voters, though, are flocking to Trump while Rubio's support drops.
Trump might have been shaky on Israel, seemed to call for a massive troop deployment to Syria and dismissed Tiananmen Square as a riot.
But Trump is certain he has tapped into something, and sees no political reason at this point to tone down his provocative comments on Muslims.
That much was clear when Trump was asked whether he stood by his claim that all of Islam hates the United States. "A lot of them" do, he said.
4. Rubio's strong night
Rubio seemed to revert to form Thursday night.
Instead of hounding Trump with rapid-fire attacks that had the effect of diminishing him, as he did at the previous debate, Rubio flashed the optimistic message that excited donors and supporters in the first place.
He displayed his foreign policy expertise -- an advantage he has over the rest of the GOP field -- to make a sober case against Trump.
"Presidents can't just say anything they want. It has consequences around the world," he said in a spirited exchange about Trump's comments on Islam.
Rubio also won over the hometown crowd with his attack on President Barack Obama's move to open up diplomatic and economic relations with Cuba.
"Here's a good deal -- Cuba has free elections, Cuba stops putting people in jail for speaking out, Cuba has freedom of the press. ... And you know what? Then we can have a relationship with Cuba. That's a good deal," Rubio said.
Will it be enough to turn Trump's 2-to-1 lead in the Florida polls upside down before Tuesday's election? Perhaps not. But Rubio is only 44 years old -- and replacing the negative impression he might have left in recent days was important both now and for his long-term future.
After the debate, Rubio said he's done with the personal Trump attacks and that he'll "never go back into that gutter again" because it conflicts with his faith and with his family's expectations of him.
"I regret doing that very much," he told CNN's Wolf Blitzer, "and I'll never do that again."
5. Republicans sound like Democrats on trade
Protectionism is all the rage in the Republican Party, and it's not just Trump's drumbeat of China-bashing.
The best indicator of how Trump has changed 2016's landscape was that the entire presidential slate of America's traditionally pro-trade party fielded a question about the topic by ripping free trade with the kind of populist talk that typically comes out of union halls and liberal interest groups.
Sure, they said they like trade in theory. But they all lambasted it in practice.
Rubio criticized the North American Free Trade Agreement, saying the United States has made a bad deal with Mexico.
Cruz dismissed international negotiations over a deal that would eliminate barriers to service industry trade as "another treaty to allow services to come in and take jobs from Americans as well."
Kasich blasted the World Trade Organization, dismissing the trade arbiter as "some international bureaucrat," and suggested that the United States needs new ways to impose taxes on foreign goods.
This was Trump's turf, though, and he pitched himself as the only one capable of striking better trade deals.
"I'm the one that knows how to change it. Nobody else on this dais knows how to change it like I do. Believe me," Trump said.