body {
  margin: 0;
}

.intro {
  background: url("https://jdnevins.com/htmlplay/opera/Background.png"), linear-gradient(233deg, #e56420, #c22525, #3d9c31, #37bbde);
  width: 100%;
  height: 100vh;
  background-size: cover;
  background-blend-mode: hard-light;
  -webkit-animation: hue-rotate 3s linear infinite;
          animation: hue-rotate 3s linear infinite;
}

@-webkit-keyframes hue-rotate {
  from {
    -moz-filter: hue-rotate(0);
    -ms-filter: hue-rotate(0);
    filter: hue-rotate(0);
  }
  to {
    -moz-filter: hue-rotate(360deg);
    -ms-filter: hue-rotate(360deg);
    filter: hue-rotate(360deg);
  }
}

@keyframes hue-rotate {
  from {
    -moz-filter: hue-rotate(0);
    -ms-filter: hue-rotate(0);
    filter: hue-rotate(0);
  }
  to {
    -moz-filter: hue-rotate(360deg);
    -ms-filter: hue-rotate(360deg);
    filter: hue-rotate(360deg);
  }
}
.center {
  display: block;
  margin-left: auto;
  margin-right: auto;
  width: 380px;
  margin-bottom: auto;
  margin-top: auto;
    padding: 20px;
}