function debut(){
  document.getElementById("button").onmouseover= rollover;
  document.getElementById("button").onmouseout= rollout;
  document.getElementById("fermer").onclick= fermer;
  document.getElementById("fermer").onmouseover= rollover2;
  document.getElementById("fermer").onmouseout= rollout2;  
}

function rollover(){
  document.getElementById("button").src = "../deco/envoyer_b.jpg";
}

function rollout(){
  document.getElementById("button").src = "../deco/envoyer.jpg";
}

function rollover2(){
  document.getElementById("fermer").src = "../deco/croix_b.gif";
}

function rollout2(){
  document.getElementById("fermer").src = "../deco/croix.gif";
}

function fermer(){
  document.getElementById("reponseformulaire").style.visibility = "hidden";
}