Meghan Markle made sure to follow Queen Elizabeth II's fashion rules for their first joint engagement.

The "Suits" star stepped out with Prince Harry for the Commonwealth Day service wearing nude stockings. According to reports, Queen Elizabeth II's fashion rules require females in the royal family to wear this.

Meghan's Mirror editor Christine Ross explained to E! News that wearing nude stockings or pantyhose is a general rule for conservative royal events. In addition, it serves its purpose especially that it's chilly in London.

"The perception is that pantyhose are more modest and feminine, but given how chilly London can be, it may be a practical choice more than anything!" Ross said. "Although pantyhose are not required for every event, they are generally a rule for more formal or conservative royal events."

It can be remembered that Markle did not comply with this rule when she and Prince Harry announced their engagement. The "Horrible Bosses" actress stirred controversy for appearing bare-legged in public.

"You never see a royal without their nude stockings. Meghan, from what I can see from the engagement photographs, it doesn't look like she was wearing tights or stockings," royal family expert Victoria Arbiter told Insider (via InStyle). "I would say that's really the only hard, steadfast rule in terms of what the queen requires."

However, although Markle followed the queen's fashion protocol, her legs did not escape her bashers' notice. Good Housekeeping noted that there were still "horrible and mean-spirited criticisms" about the future royal's legs.

In related news, Markle recently paid tribute to Princess Diana with her  Commonwealth Day outfit. Prince Harry's wife-to-be opted to wear a hat and coat made by the late Princess of Wales' favorite designers.

Markle sported a white Amanda Wakeley coat and a Stephen Jones hat. Wakeley is a good friend of Princess Diana. Meanwhile, Jones created a series of berets for Prince Harry's mom when she was just 20 years old.

Markle and Princess Diana are often compared due to their similarities. Both hug their fans in public. However, former royal butler Grant Harrold advised Markle to be careful in whatever she does when she officially becomes a royal.

"She has to be careful what she says, how she says it, and how it's taken because after the 19th of May, it will be very much the reflection of the royal family," Harrold explained. "It's every day things—from the way she walks, the way she speaks, the things she does, how she eats, how she holds her cup, how she dresses—everything will be looked at the right way or the wrong way... There will be a lot for her to adapt to."