Middleton donned the cheery Aimee Polka Dot Dress, which, at a retail price of $2,150, certainly falls on the higher end of her fashion spectrum. (She is a princess, after all.)But while the sweet cerulean and classic polka-dot pattern aren't a surprising choice, the discreet side slit proves it that this pick is no ordinary number for the duchess, who Vogue describes as "quietly redefining the 'Sloane Ranger' style for the modern, millennial set." No pressure.Subtly tufted shoulders soften the sweet-but-sexy shirtdress, while nude pumps and minimal accessories complete the look without competing with it.All of this just goes to show: If you want to update an oft-overlooked wardrobe staple like the shirtdress, keep it simple. And maybe ask yourself: What would Kate Middleton do?