body
  {
    margin-top: 55; padding: 0;
    background: #000000;
  }
  
ul {
  position:relative;
  list-style:none;
  padding: 0px;
  margin: 0px;
  width:800px;
  height:600px;
  background: url(../images/fond_accueil.jpg) no-repeat;
}
ul a {
  position:absolute;
  display:block;
  width:194px;
  height:57px;
  text-decoration:none;
}
ul a:hover{
  width:194px;
  height:57px;
}

#lien1 {
  top: 350px;
  left: 47px;
  background: url(../images/pic_acc_ref.jpg) no-repeat;
}
#lien1:hover {
  top:350px;
  left:47px;
  background: url(../images/pic_acc_ref_over.jpg) no-repeat;
}
#lien2 {
  top:8px;
  left:161px;
  background: url(../images/pic_acc_news.jpg) no-repeat;
}
#lien2:hover {
  top:8px;
  left:161px;
  background: url(../images/pic_acc_news_over.jpg) no-repeat;
}
#lien3 {
  top:86px;
  left:6px;
  background: url(../images/pic_acc_ag.jpg) no-repeat;
}
#lien3:hover {
  top:86px;
  left:6px;
  background: url(../images/pic_acc_ag_over.jpg) no-repeat;
}
#lien4 {
  top:425px;
  left:525px;
  background: url(../images/pic_acc_contact.jpg) no-repeat;
}
#lien4:hover {
  top:425px;
  left:525px;
  background: url(../images/pic_acc_contact_over.jpg) no-repeat;
}
#lien5 {
  top:157px;
  left:566px;
  background: url(../images/pic_acc_port.jpg) no-repeat;
}
#lien5:hover {
  top:157px;
  left:566px;
  background: url(../images/pic_acc_port_over.jpg) no-repeat;
}