"Birds of Prey" — starring Margot Robbie, Ewan McGregor, and Mary Elizabeth Winstead — is in theaters Friday.

In January, a tweet went viral for suggesting the film wouldn't do well because the characters don't have sex appeal.

"BoP" costume designer Erin Benach told Insider she set out to design looks that reflected the way she "would love to portray women."

That included making looks that weren't purely sexy, but ones that were also practical and that made the cast feel comfortable and empowered.

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At the end of January, a tweet about Warner Bros.' upcoming "Birds of Prey" movie starring Margot Robbie started to pick up steam after user Matthew Kadish suggested the female-centric movie would flop.

"You know why #BirdsofPrey is going to bomb just like #CharliesAngels did?" the tweet reads. "They've removed any sex appeal these characters had to appeal to a female 'girl power' audience instead of the core male comic book audience. They literally don't know who they're making this movie for."

The tweet started to receive backlash for insinuating the film's female characters needed to wear sexy clothes in order for the movie to succeed.

Insider asked "Birds of Prey" costume designer Erin Benach if she had seen the tweet and her response to it.

"I think by nature of hiring me it was sort of just implied that what I was going to create was going to be something with great design and iconic looks and an homage to the characters that so many people know and adore and love," Benach told Insider.

Here's a look at some of the core character designs from Benach in "Birds of Prey." Claudette Barius/Warner Bros

"I designed for the characters," Benach continued. "I designed the way I would design, the way I would love to portray women."

That includes making sure the costumes for characters Harley Quinn, Huntress, Black Canary, and more weren't just fun, but functional and practical so that it made sense for the women to do stunts and battle in their costumes realistically.

Benach told Insider there were several versions of Harley Quinn's gold jumpsuit made. Gussets, or extra material, were sewn into the looks so Margot Robbie and a stunt double could look natural while bending and moving.

Erin Benach said Harley's gold jumpsuit took the longest to design. Warner Bros.

"I wanted women and men to look at them and think they were beautiful and cool and awesome and sexy and strong," said Benach.

In the film's production notes, Benach said she "wasn't interested in creating a bunch of purely sexy looks, but designs these women could feel great in."

People have already started embracing the character's many looks. Insider attended a "Birds of Prey" fan event on January 23 where women were dressed up in variations of Harley Quinn's ensembles while waiting to see Margot Robbie and the cast. Warner Bros. also had a number of Harley look-alikes for fans to pose with.

A group of Harley Quinn look-alikes are seen at Warner Bros.' Harleywood event on Thursday, January 23, 2020. Kirsten Acuna/Insider

Expect this to continue to be a popular look at Con events throughout the year as well as Halloween.

"I love it," said Benach of seeing people dress up in the looks she designed. "I went to the Harley event the other night and there were 15 girls that skated up to me in a full jumpsuit and I was just like, "Ah! No way." It was awesome."

These are two of the Harley Quinn-inspired looks you can get at Hot Topic. Kirsten Acuna/Insider

Hot Topic is currently selling several looks inspired by Harley and the other "Birds of Prey" characters. A store Insider visited at Hollywood & Highland in Los Angeles, California, was already sold out of Harley's caution tape jacket, which is featured prominently in the movie.

According to box-office estimates, "Birds of Prey" is currently tracking for a $50 million opening weekend.

Insider has reached out to Kadish for comment.