a{
color: rgb(0,0,0);
}  

a:link {
text-decoration: underline;
}

a:hover {
color:yellow;
text-decoration: underline;
}

a.link:hover {
color:yellow;
background-color: #CA2C13;
}

a.gruppo {
color:black;
background-color: white;
text-decoration: underline;
}

a.gruppo:hover {
color:white;
background-color: black;
}

a.cosa {
color: red;
}

a.cosa:hover {
color: yellow;
background-color: red;
}