html,
body {
  margin: 0;
  width: 100%;
  height: 100%;
  overflow: hidden;
  background:
    linear-gradient(rgba(0, 0, 0, 0.62), rgba(0, 0, 0, 0.78)),
    url('../spaceinvaders/sprites/background.png') center / cover no-repeat fixed;
  display: grid;
  place-items: center;
  color: #fff;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

.shell {
  position: relative;
  width: min(100vw, 800px);
  aspect-ratio: 4 / 3;
}

canvas {
  width: 100%;
  height: 100%;
  display: block;
  image-rendering: pixelated;
  background: rgba(0, 0, 0, 0.78);
  border: 2px solid rgba(255, 255, 255, 0.28);
}

.qr {
  position: absolute;
  left: 50%;
  top: 50%;
  width: min(36vw, 250px);
  height: min(36vw, 250px);
  transform: translate(-50%, -50%);
  display: grid;
  place-items: center;
  padding: 12px;
  background: #fff;
  border: 4px solid #ffd447;
  box-shadow: 0 16px 42px rgba(0, 0, 0, 0.55);
}

.qr.hidden {
  display: none;
}

.qr img,
.qr canvas {
  display: block;
  width: 100%;
  height: 100%;
  border: 0;
}

.hint {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 10px;
  text-align: center;
  color: rgba(255, 255, 255, 0.52);
  font-size: 12px;
  letter-spacing: 0;
  pointer-events: none;
}