body, html {
  margin: 0;
  padding: 0;
  overflow: hidden;
  background: skyblue;
  height: 100%;
  font-family: sans-serif;
}

#game {
  position: relative;
  width: 100vw;
  height: 100vh;
  overflow: hidden;
}

#score {
  position: absolute;
  top: 10px;
  left: 10px;
  font-size: 24px;
  color: white;
  text-shadow: 1px 1px 2px black;
}

.bird {
  position: absolute;
  cursor: pointer;
  transition: transform 0.5s;
}

.bird.falling {
  transition: none;
  animation: fall 1s linear forwards;
}

@keyframes fall {
  to {
    transform: translateY(500px) rotate(720deg);
    opacity: 0;
  }
}