.supprimer , .monter , .descendre , .code_acces , .pourcentage {
  background:transparent url(/images/picto/supprimer.gif) no-repeat top left;
  width:18px;
  height:18px;
  border:none;
  color:rgba(0,0,0,0);
}

.monter{background-image:url(/images/picto/monter.gif);}
.descendre{background-image:url(/images/picto/descendre.gif);}
.code_acces{background-image:url(/images/picto/article_texte.png);}
.pourcentage{background-image:url(/images/picto/pourcentage.png);}