SPOILER ALERT: This story contains spoilers from Season 3 of “Bridgerton,” now streaming on Netflix.

Nothing’s wrong with being “Confident,” at least according to one Miss Cressida Cowper. Her stunning red revenge dress in episode 6 of “Bridgerton” season 3 comes with a side of lies: Cressida pretending to be Lady Whistledown.

While costume designer John Glaser says the red dress was dictated in the script, he felt the need to make the gown into an entrance dress, complete with a huge bow in the back.

“It’s translucent, so it’s not giant, heavy,” Glaser says. “It still has mystery to it. You’re not really sure where it stops, where it starts and you’re not really sure if it’s a red dress.”

Glaser attributes the color ambiguity to the layering in the dress: the under fabrics of the gown were hot pink, with the over fabric a deep burgundy, creating a dynamic red.

As for Cressida’s fashion throughout the season, Glaser says the costume team heightened her sleeves, creating an almost shoulder pad-esque feel to her gowns, to “give her some armor” because of her shifting storylines throughout the season.

He says while they were unable to amp up the shoulders for episode 6’s red dress, the bow in the back added to her protection.

Related video: A Day On the Set of Bridgerton’s Season 3 Finale (Dailymotion)

“It’s like an F-U dress when she walks in,” Glaser says.

As for the true Lady Whistledown, Glaser says styling Nicola Coughlin for her leading season involved changing her silhouette from the classic Regency style to a bit later in the period toward 1820. He explained that her shift in wardrobe allows viewers to see that she’s taken control of her life, no longer following the gaudy colors and costumers her mother forced upon her in previous seasons.

Different historical Hollywood stars like Marilyn Monroe, Grace Kelly and Audrey Hepburn’s styling also inspired Penelope this season: “When you look at someone that’s famous in one of those black and white photos…you remember how beautiful they are, but you really don’t remember what they’re wearing. And that’s what we were trying to achieve. It’s like what they’re wearing is beautiful, but it’s not something that you notice, it’s just part of them.”

He said the team also took her colors down and softened them to ensure that they wouldn’t be distracting, and to allow her character to shine and come to life and keep up her secret identity as Whistledown.

Glaser says that the team looked at all types of research from all periods and tried to incorporate as much from the Regency era as possible, but that the show is: “Fantasy. You always have to remember this show is fantasy. It’s not a history lesson. It’s a gift.”