Once the go-to shoe for tech bros, Allbirds is pivoting in response to declining sales and designing for a new kind of customer: women who care about what’s on their feet. On a recent stroll by my local Allbirds store in Harvard Square, I had to do a double take. In the window, the brand was advertising its new Varsity collection: a ’70s-inspired sneaker line with a rubber sole and a feminine color palette that weaves together pink, olive green, mustard, and brick red. It’s an unmistakably fashionable shoe that wouldn’t look out of place at New Balance and Saucony, or even Valentino and Celine.