body {
  width: 100vw;
  height: 100vh;
  margin: 0;
  padding: 0;
  background: #ddd;
  font-family: Arial;
}
header,
footer,
article {
  margin: auto;
  max-width: 1024px;
  padding: 16px;
}
header {
  background: salmon;
}
footer {
  background: #fcaca3;
}
article {
  background: #fff;
}
article #reader-container {
  width: 100%;
  height: 512px;
}