div.jumbotron {
  background-image: url("../images/kura.jpg");
  background-size: cover;
  background-color: #000;
  color: white;
  position:relative;
  height:500px;

}

a.white:link { color:white } 
a.white:visited { color:darkgray } 
a.white:hover { color:lightgray } 
a.white:active { color:darkgray }