style.css

body {
	background-color: black;
	font-family: Arial;
        overflow: hidden;
}

h1 {
	color : white;
	text-shadow: gray 1px 0 10px;
}

.button-85 {
  rotate: 270deg;
  text-shadow: gray 1px 0 10px;
  padding: 35px 10px;
  font-size: 30px;
  font-weight: 400;
  border: none;
  outline: none;
  color: white;
  background: #111;
  cursor: pointer;
  position: relative;
  z-index: 0;
  border-radius: 10px;
  user-select: none;
  -webkit-user-select: none;
  touch-action: manipulation;
  transform: translateX(0);
  transition: transform 150ms, box-shadow 150ms;
}

.button-85:before {
  content: "";
  background: linear-gradient(
    45deg,
    #ff0000,
    #ff7300,
    #fffb00,
    #48ff00,
    #00ffd5,
    #002bff,
    #7a00ff,
    #ff00c8,
    #ff0000
  );
  position: absolute;
  top: -2px;
  left: -2px;
  background-size: 400%;
  z-index: -1;
  filter: blur(5px);
  -webkit-filter: blur(5px);
  width: calc(100% + 4px);
  height: calc(100% + 4px);
  animation: glowing-button-85 20s linear infinite;
  transition: opacity 0.3s ease-in-out;
  border-radius: 10px;
}

@keyframes glowing-button-85 {
  0% {
    background-position: 0 0;
  }
  50% {
    background-position: 400% 0;
  }
  100% {
    background-position: 0 0;
  }
}

.button-85:after {
  z-index: -1;
  content: "";
  position: absolute;
  width: 100%;
  height: 100%;
  background: #222;
  left: 0;
  top: 0;
  border-radius: 10px;
}

.button-85:hover {
  box-shadow: rgba(0, 0, 0, .15) 0 3px 9px 0;
  transform: translateX(2px);
}

@media (min-width: 768px) {
  .button-85 {
    padding: 35px 10px;
  }
}