.thumbnail:hover{
position: relative;
background-color: transparent;
}
.thumbnail span{
position: absolute;
background-color: lightyellow;
padding: 10px;
left: 100px;
border: 1px solid gray;
visibility: hidden;
color: black;
text-decoration: none;
width:300px;
}
.thumbnail:hover span{ 
visibility: visible;
top: 40px;
left: 60px;
}