body {
  width: 100%;
  height: 100%;
  margin: 0;
  padding: 0;
  background: #ddd;
  font-family: Arial;
  
}
header,
footer,
article {
  margin: auto;
  max-width: 100%;
  padding: 0px;
}
header {
  background: salmon;
}
footer {
  background: #fcaca3;
}
article {
  background: #fff;
}
article #reader-container {
    width: 100%;
  height: 100%;
  position: center;
}