body {
  margin: 0;
  padding: 0;
  padding-top: 1em;
  padding-bottom: 1em;
  padding-left: 10em;
  padding-right: 10em;
  position: relative;
}

#header {
  background-color: blue;
  width: 100%;
  line-height: 1.5;
  position: absolute;
  left: 0;
  top: 0;
}

#left {
  background-color: yellow;
  width: 10em;
  position: absolute;
  left: 0;
  top: 1.5em;
}

#right {
  background-color: red;
  width: 10em;
  position: absolute;
  right: 0;
  top: 1.5em;
}

#footer {
  background-color: blue;
  width: 100%;
  position: absolute;
  bottom: 0;
  left: 0;
}