index.css

html,
body {
  -webkit-text-rendering: optimizeLegibility;
  -webkit-tap-highlight-color: transparent;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  -webkit-overflow-scrolling: touch;
  -webkit-touch-callout: none;

  text-rendering: optimizeLegibility;
  font-family: 'Creepster', cursive;
  font-variant-ligatures: none;
  backface-visibility: hidden;
  background-color: #222222;

  text-size-adjust: none;
  letter-spacing: normal;
  line-height: 1.4rem;

  font-display: block;
  font-weight: normal;
  font-kerning: none;
  font-style: normal;
  font-size: 1rem;

  user-select: none;
  appearance: none;
  overflow: hidden;

  max-height: 100%;
  min-height: 100%;

  max-width: 100%;
  min-width: 100%;

  height: 100%;
  width: 100%;

  padding: 0;
  margin: 0;
}

#tap {
  transform: translate(-50%, -50%);
  transition: opacity 0.5s;
  letter-spacing: 0.25rem;

  pointer-events: none;
  position: absolute;
  font-size: 5rem;
  color: #8A0707;

  display: block;
  margin: auto;

  padding: 0;
  opacity: 0;

  left: 50%;
  top: 50%;
}

#tap.visible {
  opacity: 1;
}

#dance {
  background-color: transparent;
  border: 0.125em solid #8A0707;

  text-transform: uppercase;
  transition: opacity 0.5s;

  box-sizing: border-box;
  pointer-events: none;

  position: absolute;
  font-size: 1.5rem;

  cursor: pointer;
  display: block;
  bottom: 0.5em;

  margin: 0 auto;
  color: #8A0707;
  outline: none;

  padding: 0;
  opacity: 0;
  width: 5em;

  top: auto;
  right: 0;
  left: 0;
}

#dance.visible {
  transition-delay: 1.0s;
  pointer-events: all;
  opacity: 1;
}

#fullscreen {
  background-image: url('./assets/fullscreen.png');
  background-color: transparent;
  background-repeat: no-repeat;
  background-position: center;
  background-size: cover;

  position: absolute;
  cursor: pointer;
  display: block;

  height: 2.36em;
  width: 2.36em;

  outline: none;
  border: none;

  bottom: 1em;
  right: 1em;

  padding: 0;
  margin: 0;
}