index.scss

body {
  font-family: "Helvetica", "Arial", sans-serif;
  line-height: 1.5;
  color: #555;
  background-color: #fff;
  padding: 0px;
  margin-top: 0px;
  margin-left: 0px;
  overflow: hidden;
}

.container {
  background-image: url('./bg.png');
  animation: noise 1s steps(8,end) infinite both;
  width: 200vw;
  height: 200vh;
  margin-top: -50vh;
  margin-left: -50vw;
  position: absolute;
  overflow: hidden;
}

button {
  font-size: 6rem;
  border-radius: 50%;
  border: none;
  box-shadow: #619 5px 5px;
  cursor: pointer;
  color: #fff;
  background-color: #83b;
  padding: 10px;
  padding-bottom: 25px;
  padding-left: 15px;
  min-width: 1.4em;
  position: relative;
  left: -50%;

  &:hover {
    box-shadow: #619 7px 7px;
    margin-top: -2px;
  }

  &:active {
    box-shadow: #619 3px 3px;
    margin-top: 2px;
  }
}

.btn {
  position: absolute;
  left: 50%;
  top: 200px;
}

.hide {
  display: none;
}

@keyframes noise {
  0% {
    transform: translateX(0px,0px); }
  10% {
    transform: translate(-100px, 100px);
  }
  20% {
    transform: translate(150px, -100px);
  }
  30% {
    transform: translate(-100px,100px);
  }
  40% {
    transform: translate(100px, -150px);
  }
  50% {
    transform: translate(-100px, 200px);
  }
  60% {
    transform: translate(-200px, -100px);
  }
  70% {
    transform: translateY(50px, 100px);
  }
  80% {
    transform: translate(100px, -150px);
  }
  90% {
    transform: translate(0px, 200px);
  }
  100% {
    transform: translate(-100px, 100px);
  }
}