html { 
  background: url(px/bg.png) no-repeat center center fixed; 
  -webkit-background-size: cover;
  -moz-background-size: cover;
  -o-background-size: cover;
  background-size: cover;
}

body {background-color: transparent; }

div.jumbotron{margin: 80px 0; text-align: center;  }

.logo { width: 100px; border: none; }