style.css

html, body {
  background-color: #000;
  color: #eee;
  margin: 0px;
  padding: 0px;
  position: fixed;
  overflow: hidden;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;

  /* Prevent user selection. */
  user-select: none;
  touch-callout: none;
  -webkit-touch-callout: none;
  -webkit-user-select: none;
}
.dialog {
  display: none;
  align-items: center;
  justify-content: center;
  font-family: sans-serif;
  font-size: 170%;
  position: absolute;
  width: 100%;
  height: 100%;
  background: rgba(255, 255, 255, 0.2);
  -webkit-user-select: none;
  -moz-user-select: none;
  user-select: none;
}
.dialog.visible {
  display: flex;
}
.dialog .wrap {
  padding: 30px 60px;
  margin: 20px auto;
  width: 60%;
  background: rgba(0, 0, 0, 0.8);
  border-radius: 5px;
}
.dialog h1 {
  margin: 0;
}

a, a:visited {
  color: skyblue;
}

#watermark img {
  position: fixed;
  overflow: hidden;
  left: 0;
  bottom: 0;
  opacity: 0.3;
  width: 24px;
  height: 24px;
  padding: 12px;
  -webkit-user-select: none;
  -moz-user-select: none;
  user-select: none;
}
#watermark img:hover {
  opacity: 1;
  -webkit-filter: drop-shadow(white 0 0 5px);
}


canvas {
  cursor: -webkit-grab;
}
canvas:active {
  cursor: -webkit-grabbing;
}

#play-overlay {
  position: fixed;
  width: 100%;
  height: 100%;
  left: 0;
  top: 0;
  right: 0;
  bottom: 0;
  background-color: rgba(0, 0, 0, 0.5);
  display: none;
	align-items: center;
  justify-content: center;
}
#play-overlay.visible {
	display: flex;
}
#play-overlay img {
  width: 30%;
  height: 30%;
}

#error .message {
  font-family: monospace;
}