html, body {
  margin: 0;
  padding: 0;
  height: 100%;
  overflow: hidden;
  font-family: sans-serif;
}

.background {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-position: top;
  background-size: cover;
  opacity: 0.6;
  transition: background-image 2s ease-in-out;
  z-index: -1;
  background-color: rgba(0, 0, 0, 0.3);
  background-blend-mode: overlay;
}

.content {
  position: relative;
  z-index: 1;
  text-align: center;
  padding-top: 20%;
  color: white;
}