a.annotation {
position: absolute;
border: 2px groove red;  
padding: 0;  
display: none;
}

a.annotation span {  
display: block;  
background: white;  
width: 100%;  
height: 100%;  
opacity: 0.3; 
-moz-opacity: 0.3;  
filter:alpha(opacity=10);}

a.annotation:hover {  
border-color: blue;
}

img.annotated {  
border-width: 0;
}