body {
  font-family: sans-serif;width: 800px; margin-left: auto; margin-right: auto;
}
a {text-decoration: none;}
a:link{
  color:blue
}
a:visited{
  color:green;
}
a:hover{
  color:red
}
a:active{
  text-decoration: underline;
  background-color: black;
  color:yellow
}