Wearing bright colors is also not a wise choice, since she hunts by both sight and smell, the latter depending chiefly on the amount of carbon dioxide exhaled by the potential target.
Men, it's just a suit and generally a bright tie or a bright shirt, not too dark, but black or blue pin-stripped suit but as long as it's a suit it's fine.
Harrys spirits couldn't help but lift slightly as he watched Fleur hurry back across the lawns to Madame Maxime, her silvery hair rippling in the sunlight.