The distinction between workwear and casual wear, once so clearly delineated, has never been murkier as office workers around the country push the boundaries of what is acceptable personal style at work.

Express was looking for insight on how to revitalize its business after sales hit a major slump last year. Same-store sales were down 10 percent last year and share prices fell by almost 20 percent. A white paper commissioned by Express and Chandelier Creative to explore how workwear trends have changed in the past few decades found that consumers no longer think of their wardrobes in terms of just work clothes and casual clothes.

“The differences between the two categories will become less and less over time,” said Jim Hilt, evp and chief customer experience officer at Express, in an email. “As customers’ work and personal lives blur, it’s natural their wardrobes will, too. Despite the growing number of customers that work in ‘casual’ settings, there will always be a need to look polished and put together.”

This trend is particularly noticeable on the coasts and in urban hubs in the U.S., but the casualization of the office has trickled its way into the heartland of the country as fashion trends often do. Traditional office-wear brands like Banana Republic and Ann Taylor are struggling with this change, often finding themselves left behind in favor of brands that have more of a focus on “day to night” fashion. These brands, Express included, have been forced to make major adjustments to how they design, market and sell these products to a consumer whose tastes are changing rapidly.

The whitepaper found that the majority of consumers now think that a casual dress code with lots of room for expression and personality is desirable at work. This is backed up with data from Pinterest that has seen 46 million searches across 11 million users for “work fashion,” with “stylish,” “trendy” and “edgy” all coming in as top saves for work-related fashion.

“We saw the staggering amount of people searching on Pinterest for workwear style advice,” said Michael Scanlon, creative director at Chandelier, an agency that worked closely with Express on its latest workwear campaign and the accompanying whitepaper. “A lot of the rules are so archaic; it’s a very corporate and monolithic mentality. But if you look at the trend of personal style, it’s changing rapidly. Workwear is something you can mix and match. A pair of black pants can be good for work or for going out.”

Express and Chandelier emphasized the weakening of old dress code rules in a campaign video called SFW (Style For Work, but also a play on the acronym NSFW – Not Safe For Work), juxtaposing audio from old instructional videos on how to dress at the office with footage of people breaking those rules while still looking appropriate for an office setting.

One of the biggest takeaways for brands is that the distinction between office attire and casual attire is becoming nonexistent. A majority of men and women surveyed said that more than half of their wardrobe can be worn both in and out of the office.

“Work is no longer just 9 to 5; it’s 9 to night,” Hilt said. “Customers are aware of the rules and guidelines of workwear, but at the same time searching for inspiration to embrace their own unique, personal style. At Express, we always want to grow and evolve with our customers, which is reflected in our new workwear assortment and our expanded definition of workwear.”

Express has historically separated its products between day wear for going to the office and night wear for going out. But consumers now want clothes that can do both, along with more options and variety for what to wear to the office on a given day. Earlier this year, Express debuted a new concept store that was divided into sections the brand calls stories, including “a space for the office worker and one for the more creative type,” among other styles.

The concept store does not distinguish between work clothes and fun clothes but rather between different types of expression in a work environment.

Express believes this is the future of workwear, moving away from the separation between work and non-work clothes and toward presenting unique flavors of style appropriate for the office or leisure.

“Fashion brands must be able to anticipate and support customer demand in order to stay relevant in today’s evolving retail market,” Hilt said.