As previously noted, women are having trouble keeping their crotches covered up at Cannes this year. That red-carpet staircase is steep, the skirt-slits are high, and apparently panties aren't a priority during the dressing process. But Jessica Chastain will not fall victim to the Cannes Stairs of Doom: Nay, she was prepared. Not only was the slit up the front of her purple Givenchy gown relatively conservative, but she also took extra precautions by wearing what appear to be matching Spanx underneath. They are literally the exact same color as her dress, leading us to wonder if Riccardo Tisci custom-dyed them for her. Wouldn't that be brilliant? Why don't designers do this for their red-carpet clients all the time, as a rule? Meanwhile, well done to Chastain for making her first red-carpet underwear-flash look respectable, even endearing.