body {
  margin: 0;
  padding: 0;
  font-family: sans-serif;
}

section * {
  margin: 10px;
}

header {
  background-color: #222;
  height: 150px;
  padding: 20px;
  color: white;
}

.center {
  text-align: center;
}

pre {
  background-color: bisque;
  min-height: 100px;
  margin: 0px;
  padding: 10px;
}

.loader {
  text-align: center;
  height: 64px;
  margin-bottom: -64px;
}

.loading .lds-ripple {
  display: inline-block;
  position: relative;
  width: 64px;
  height: 64px;
}
.loading .lds-ripple div {
  position: absolute;
  border: 4px solid #000;
  opacity: 1;
  border-radius: 50%;
  animation: lds-ripple 1s cubic-bezier(0, 0.2, 0.8, 1) infinite;
  margin: auto;
}
.loading .lds-ripple div:nth-child(2) {
  animation-delay: -0.5s;
}
@keyframes lds-ripple {
  0% {
    top: 28px;
    left: 28px;
    width: 0;
    height: 0;
    opacity: 1;
  }
  100% {
    top: -1px;
    left: -1px;
    width: 58px;
    height: 58px;
    opacity: 0;
  }
}