html, body {
  height: 100%;
  margin: 0;
}

.bg-image {
  /* Full height */
  height: 100%;
  /* Center and scale the image */
  background-position: center;
  background-repeat: no-repeat;
  background-size: cover;
  /* Set the background image */
  background-image: url('http://umbrel.local/wallpapers/6.jpg');
}

.content {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  color: #ffffff;
  text-align: center;
  font-size: 36px;
}

@media (max-width: 768px) {
  .content {
    font-size: 24px;
  }
}