body {
 background-image: url("windows_7_23.jpg"); 
}
h1 {
  border: 20px solid #000000;
  background: #FFD700;
  font-family: Times;
}

.header {
  border: 20px solid #000000;
  padding: 0px;
  text-align: center;
  background: #D83131;
  color: #000000;
  font-size: 30px;
  font-family: Verdana;
}
.aside {
  float: left;
  border: 20px solid #000000;
  background: #D83131;
  font-family: Verdana;
  padding: 0px;
}
iframe {
  border: 20px solid #000000;
  
}
.multiplex {
  text-align: center;
  position: absolute;
  top:175px;
}