html {
background: url(wurzel.jpg) no-repeat center center fixed;
   -webkit-background-size: cover;
   -moz-background-size: cover;
   -o-background-size: cover;
   background-size: cover; 
}

#wissent {
  position: fixed;
  width: 30%;
  height: auto;
  Bottom: 0px;
  right: 10%;
  z-index: 15;
}

#abstand {
   height: 100%;
   background-color: transparent;
}

</style>