body {
  background-image: linear-gradient(to left, violet, indigo, blue, green, yellow, orange, red);
}

@media (max-width:480px) {
  img#optionalstuff {
    display: none;
  }
}
img {
  max-width: 100%;
}

@media (max-width:480px) {
  div#optionalstuff {
    display: none;
  }
}
html {
    height: 100%;
}
body {
    height: 100%;
    width:100%;
    margin: 0;
    background-repeat: no-repeat;
    background-attachment: fixed;
}
html, body {
    max-width: 100%;
    overflow-x: hidden;
}
.marquee {
  width: 80%;
  line-height: 50px;
  white-space: nowrap;
  overflow: hidden;
  box-sizing: border-box;
}
.marquee h1 {
  display: inline-block;
  padding-left: 100%;
  animation: marquee 15s linear infinite;
  background: -webkit-linear-gradient(left, violet , blue, cyan, green, yellow, orange);
  background: -o-linear-gradient(right, violet , blue, cyan, green, yellow, orange);
  background: -moz-linear-gradient(right, violet , blue, cyan, green, yellow, orange);
  background: linear-gradient(to right, violet , blue, cyan, green, yellow, orange);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}
@keyframes marquee {
  0%   { transform: translate(0, 0); }
  100% { transform: translate(-100%, 0); }
}