html, body{
  height: 100%;
}

body { 
  background-image: url(background.png) ;
  background-position: center center;
  background-repeat:  no-repeat;
  background-attachment: fixed;
  background-size:  cover;
  background-color: #999;
}

div, body{
  margin: 0;
  padding: 0;
  font-family: exo, sans-serif;
  
}
.wrapper {
  height: 100%; 
  width: 100%; 
}

.message {
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  box-sizing: border-box;
  width: 100%; 
  height:45%;
  bottom: 0; 
  display: block;
  position: absolute;
  background-color: rgba(0,0,0,0.6);
  color: #fff;
  padding: 0.5em;
}