a.tip { 
    position: relative; 
} 

a.tip span { 
    display: none; 
    position: absolute; 
    top: 20px; 
    left: -10px; 
    width: 160px; 
    padding: 5px; 
    z-index: 100; 
    background: #000; 
    color: #fff; 
    -moz-border-radius: 5px; /* this works only in camino/firefox */ 
    -webkit-border-radius: 5px; /* this is just for Safari */ 
} 

a:hover.tip { 
    font-size: 99%; /* this is just for IE */ 
} 

a:hover.tip span { 
    display: block; 
}