@page {
  margin: 0;
}
html, body {
  display: block;
  font-size: 1em;
  line-height: inherit;
  height: 100%;
  margin: 0;
  padding: 0;
  border-width: 0;
  oeb-column-number: 1;
}
.cover {
  text-align: center;
}
.cover_img {
  max-width: 100%;
  width: auto;
  height: 99vh !important;
  height: 100%;
}