After Season 7, Episode 1, a lot of Game of Thrones fans were freaking out that Sansa's hair looked a lot like Cersei's, and what that could mean for her character.
It's true that Sansa's hair has been used in the past to indicate her ~influences~.
In Season 6, she seemed to return to her Northern roots.
And I actually think her Season 7 hair – especially in Episode 3 – is a continuation of this.
Specifically, her hairstyle is looking a lot closer to Cat's twists and braids.
Just, like, the bad wig version.