.biblio{
	background-image:url(img/sous_menu/background_biblio.jpg);
	background-repeat:no-repeat;
}
.activite{
	background-image:url(img/sous_menu/background_labo.jpg);
	background-repeat:no-repeat;
}
.media{
	background-image:url(img/sous_menu/background_pensine.jpg);
	background-repeat:no-repeat;
}
.prof{
	background-image:url(img/sous_menu/background_book.jpg);
	background-repeat:no-repeat;
}