When flying DL exPVG, I've experienced security checks at the gate that have consisted of hand searches of carry on items with sealed bottles of water acquired airside in the terminal being confiscated. I don't know whether duty free cosmetics would be allowed if sealed in a tamper proof container and/or delivered to the gate.

Remember also that if you have any connecting flights after arrival in the USA, your liquids must fit into the 3-1-1 baggie, although you can put them into checked luggage after exiting customs.