html,
body {
  background-color: #1f1f1f;
  height: 100%;
  overflow: hidden;
  font: caption;
  margin: 0;
  touch-action: none; /* disable default touch panning/zooming */
}

canvas {
  margin: 0;
  padding: 0;
  left: 0;
  top: 0;
  display: block; /* remove inline baseline gap */
  position: absolute; /* ensure no flow margin affects top-left */
}

.container {
  position: absolute;
  bottom: 0;
  top: 0;
  left: 0;
  right: 0;
  margin: 0;
  text-align: center;
  padding-top: 25%;
  padding-bottom: 25%;
}

p {
  color: #fff;
  font-size: 1.1em;
  text-align: center;
}

p.option {
  display: inline;
  font-size: 1.5em;
  padding-left: 12px;
  padding-right: 12px;
}

footer {
  position: absolute;
  right: 0;
  bottom: 0;
  left: 0;
  padding: 0.1em;
  text-align: center;
}

a {
  color: #ddd;
}

button {
  color: #fff;
  font-size: 2em;
  font-weight: bold;
  background-color: Transparent;
  background-repeat: no-repeat;
  border: none;
  cursor: pointer;
  display: block;
  margin: 0 auto;
  overflow: hidden;
  outline: none;
  position: relative;
  text-align: center;
  text-transform: uppercase;
}

button:hover {
  mask-image: linear-gradient(-75deg, rgba(0, 0, 0, .6) 30%, #000 50%, rgba(0, 0, 0, .6) 70%);
  mask-size: 200%;
  -webkit-mask-image: linear-gradient(-75deg, rgba(0, 0, 0, .6) 30%, #000 50%, rgba(0, 0, 0, .6) 70%);
  -webkit-mask-size: 200%;
  animation: shine 1s infinite;
}
button.iterate {
  background-color: #1d1c1c;
  font-size: 1.5em;
  display: inline;
}

@keyframes shine {
  from {
    -webkit-mask-position: 150%;
  }
  to {
    -webkit-mask-position: -50%;
  }
}