body{background-color:#000000;
}
.centrato {
font-family:Arial, Helvetica, sans-serif;
font-size:14px;
color:#FFFFFF;
text-align:center; 
  display:     block;
  width:       600px;
  height:      260px;

  position:    absolute;
  top:         50%;
  left:        50%;
/* impostare i valori margin esattamente alla metà dei valori width ed height*/
  margin:      -130px 0 0 -300px;

  background:  #000;

}

a{
color:#FFFFFF;
text-decoration:none;
}
a:hover{
text-decoration:underline;
}