* {
  margin:0px;
  padding:0px;
}
#columna1 {
  position:absolute;
  top:0px;
  left:0px;
  width:400px;
  margin-top:20px;
  background-color:#ffff55;
}
#columna2 { 
  margin-left:440px;
  margin-right:40px;
  margin-top:20px;  
  background-color:#ffffbb;
}