preview-text.css

html {
  background-color: #131516;
  color: white;
  font-size: 16px;
  height: 100%;
  line-height: 1;
}

body {
  display: grid;
  grid-template: 1fr / 1fr;
  height: 100%;
  margin: 0;
  place-items: center;
}

pre {
  margin: 0;
}

body > * {
  grid-column: 1 / 1;
  grid-row: 1 / 1;
}

body > pre {
  opacity: 0;
}