a.m123 {   position: relative;
   color: white;
   text-decoration: none;
   border-bottom: 1px gray dotted; /* On souligne le texte. */}
a.m123 span { display: none; }
a.m123:hover {
   background: none;/*IE*/ z-index: 5000; 
   cursor: pointer;}
a.m123:hover span {
   display: inline; position: absolute;
   white-space: nowrap; 
   top: 18px; left: +550px; background: black; color: white; padding: 1px; border: 0px solid green; border-left: 0px solid green;}