body {
  margin: 0;
}
div#main {
  width: auto;
  height: 100vh;
  display: block;
  background-color: #000;
  overflow: hidden;
}
div#test-area {
  width: 100%;
  height: 100%;
  background-color: #000;
  display: flex;
  justify-content: center;
  align-items: center;
}
div#test-area > .moving-zone {
  position: relative;
  width: 80%;
  height: 100px;
  margin: 30px auto;
  background-color: #555;
  border: #ccc 1px solid;
  border-radius: 50px;
}
div#test-area > .moving-zone > .moving-obj {
  background-color: #fff;
  position: absolute;
  top: 0;
  left: 0;
  width: 100px;
  height: 100px;
  border-radius: 50px;
  display: flex;
  justify-content: center;
  align-items: center;
  animation: motion-x 2s infinite;
}
div#test-area > .moving-zone > .moving-obj > img {
  width: 75%;
  height: 75%;
}
div#function-area {
  display: none;
  color: #fff;
}
div#function-area > .code {
  display: none;
  color: #fff;
}
@keyframes motion-x {
  from {
    translate: 0;
  }
  to {
    translate: calc(80cqw - 100px);
  }
}