body {background-image: url(fondo2.jpg);}

a {text-decoration: none;}

a:link {
  color: black;
  background-color: transparent;
  text-decoration: none;
}
a:visited {
  color: lightgray;
  background-color: transparent;
  text-decoration: none;
}
a:hover {
  color: red;
  background-color: transparent;
  text-decoration: underline;
}
a:active {
  color: yellow;
  background-color: transparent;
  text-decoration: underline;
}