index.css

.fheader {
    text-shadow: 2px 7px 5px rgba(0,0,0,0.3), 0px -4px 10px rgba(255,255,255,0.3);
}

.button{
  padding: 0.6em 2em;
  margin: 0.5em 0.5em 0.5em 0.5em;
  border: none;
  outline: none;
  color: rgb(255, 255, 255);
  background: rgb(32, 32, 32);
  cursor: pointer;
  position: relative;
  z-index: 0;
  border-radius: 5px;
  user-select: none;
  -webkit-user-select: none;
  touch-action: manipulation;

  display:inline-block;
  width: fit-content;

  text-decoration: none;

  transition: transform 0.2s;
}

.button: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 20s linear infinite;
  border-radius: 5px;
}

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

.button:after {
  z-index: -1;
  content: "";
  position: absolute;
  width: 100%;
  height: 100%;
  background: rgb(0, 0, 0);
  left: 0;
  top: 0;
  border-radius: 5px;
}

.button:hover {
    transform: scale(1.1) translateY(-0.3em);
}

.button:active:after {
    background: rgb(32, 32, 32);
}