.header {
  display: flex;
  flex-direction: row;
  align-items: center;
}

.header * {
  margin-right: 0.75rem;
}

.header li {
  display: inline-block;
  font-size: 1.25rem;
}

#viewer {
  width: 500px;
  height: 500px;
  position: relative;
}

.overlay {
  z-index: 1;
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  color: white;
  display: flex;
  justify-content: center;
  align-items: center;
}

.overlay.hidden {
  display: none;
}

#spin {
  max-width: 400px;
  position: relative;
}