bouton1 = new Image();
bouton1.src = "images/bout_pourquoi_over.png";

bouton2 = new Image();
bouton2.src = "images/bout_demarche_over.png";

bouton3 = new Image();
bouton3.src = "images/bout_service_over.png";

bouton4 = new Image();
bouton4.src = "images/bout_societe_over.png";

bouton5 = new Image();
bouton5.src = "images/bout_login_over.png";

bouton6 = new Image();
bouton6.src = "images/bout_contact_over.png";