Blue is the Warmest Colour actress and muss-haired French style queen Adèle Exarchopoulos nails looking smart but not too polished and prissy, by teaming her lace Peter Pan collar (mismatched to perfection with a Breton top) with a not-even-trying messy topknot.
To achieve this look, use your fingers to mess up a bun after securing it with pins. Then spritz with hairspray to hold in place. Et voilà!

Find out more about Adèle and her cool French-girl style here.