* { margin: 0; padding: 0; box-sizing: border-box; }

html, body {
  width: 100%;
  height: 100%;
  background: #000;
  overflow: hidden;
}

.bg-layer {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  background-color: #000;
  transition: opacity 1s ease-in-out;
  pointer-events: none;
  user-select: none;
  -webkit-user-select: none;
}