nav {
  width: 300px;
  position: absolute;
  /* This trasform moves the drawer off canvas. */
  -webkit-transform: translate(-300px, 0);
  transform: translate(-300px, 0);
  /* Optionally, we animate the drawer. */
  transition: transform 0.3s ease;
}
nav.open {
  -webkit-transform: translate(0, 0);
  transform: translate(0, 0);
}