After more than a year of tough talk on the campaign trail, Hillary Clinton and Donald J. Trump finally took their fight for the presidency to each other on Monday evening in their first debate.

The tense evening marked a historic event: the first female presidential nominee for a major party sparring with her opponent on live television. Though the 90-minute exchange covered topics such as national security, race relations and economic prosperity, gender politics were a constant, if not always subtle, theme.

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From Trump's frequent interruptions to his off-hand remarks to his insistence that Clinton lacked the "stamina" to be president, it appeared the Republican nominee could not quiet the instincts that have won him a reputation as impulsively contemptuous. While Trump seems eager to wield that approach against adversaries regardless of their gender, sharing the stage with Clinton highlighted his sexist tendencies.

Clinton seemed prepared for the onslaught. "I have a feeling that by the end of this evening, I'm going to be blamed for everything that's ever happened," she joked.

Here’s what it is like to be interrupted 28 times during a debate: #Debates #debatenight pic.twitter.com/Br6c8UBMTb

— Mic (@mic) September 27, 2016

Trump indeed blamed her, and didn't hesitate to make his point. During the first 26 minutes of the debate, Trump interrupted Clinton 25 times, according to Vox. Conrad Hackett, a senior demographer for the Pew Research Center, tweeted that Trump tried to cut Clinton off three times as often as she interrupted him.

When pressed by moderator Lester Holt to explain what Trump meant when he commented that Clinton doesn't have a "presidential look," he offered that she couldn't withstand the demanding pace of the presidency. Many internet commenters argued, however, that stamina is a code word for masculinity, and cast Trump's attack as an invocation of traditional gender norms.

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Clinton tried to capitalize on these revealing moments, often responding to his outbursts with a straight face, but occasionally letting loose a laugh or shrug. She delivered a few memorable retorts, including a quip about her physical and mental fortitude.

"Well, as soon as he travels to 112 countries and negotiates a peace deal, a cease-fire, a release of dissidents, an opening of new opportunities in nations around the world, or even spends 11 hours testifying in front of a congressional committee, he can talk to me about stamina," Clinton said to applause.

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Nichole Bauer, an assistant professor in the political science department at the University of Alabama who studies gender and politics, says this back-and-forth was particularly telling. Trump tried to dismiss Clinton's in-depth qualifications in domestic politics and international affairs as "bad experience," but had little to counteroffer beside his own questionable record in real estate.

Bauer, who watched the candidates' non-verbal communication style closely, says how they responded was as important as the content of their remarks.

Clinton, for instance, appeared to spend the first half of the debate smiling, perhaps given past criticism that she does not smile enough. This battle, which male candidates don't face, is nearly impossible to win; too much or too little smiling and she could be perceived as glib or humorless. And as Trump yelled his responses, Bauer noted that it would not be socially acceptable for Clinton could not do the same.

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When Clinton occasionally laughed at Trump's comments, Bauer says she risked appearing condescending. Yet the strategy is a familiar one to women trying to diffuse conflict and have few tools at their disposal because they can't afford to be perceived as nagging or reactionary.

"[Laughing] has the effect of trying to send the signal that what her opponent is saying is not credible, not serious and not something we should worry about," says Bauer. "It's saying she’s the adult in in the room."

Clinton focused on that message — and its implications for girls and women — in the days preceding the debate. On Friday, her campaign debuted an emotional ad featuring adolescent girls looking at their own appearance as clips of Trump play in the background. He makes comments like: "I'd look her right in that fat, ugly face of hers" and "she's a slob."

If the young women of this country have Donald Trump as their president, what will they think of themselves? pic.twitter.com/1IrjWddzzy

— Hillary Clinton (@HillaryClinton) September 24, 2016

While Trump congratulated himself for not resorting to the cruelest of attacks during the debate — an apparent reference to Bill Clinton's infidelities — he did little to assure voters that he can respond to criticism from a woman without becoming unhinged.

When Clinton pointed out the numerous comments Trump has made about women he dislikes, he said at least one of them, Rosie O'Donnell, deserved it.

"I said very tough things to her," Trump said, "and I think everybody would agree that she deserves it and nobody feels sorry for her."

He also complained that Clinton has aired commercials that he feels are unrepresentative of his positions. "It's not nice. And I don't deserve that," Trump said.

Clinton shows no signs of relenting. Following the debate, her campaign released a new video featuring Alicia Machado, a Clinton supporter and former Miss Universe who says being subjected to Trump's alleged insults during her reign in the 1990s led her to develop eating disorders.

Donald Trump called her "Miss Piggy" and "Miss Housekeeping."

Her name is Alicia Machado. #DebateNight pic.twitter.com/0wrISjJe6z

— Hillary Clinton (@HillaryClinton) September 27, 2016

Though she didn't appear on the debate stage, Machado may be the most powerful Clinton surrogate of the night. In the video, Machado, who is now a U.S. citizen, voices Clinton's charge that Trump is unprepared to become president.

"This is a man who doesn't realize the damage he causes," she says.