Starbucks workers are striking over the chain's new dress code

Starbucks' new dress code for baristas has sparked a strike at 75 U.S. stores, with more than 1,000 workers protesting the new policy, a union representing the coffee giant's workers said Wednesday.

The new dress code, which went into effect on Monday, requires employees at company-operated and licensed stores in the U.S. and Canada to wear a solid black shirt and khaki, black or blue denim bottoms under their green apron.

Under the previous dress code, baristas could wear a broader range of dark colors and patterned shirts. Starbucks said the new rules would make its green aprons stand out and create a sense of familiarity for customers as it tries to establish a warmer, more welcoming feeling in its stores.