body {
  margin: 0;
  text-align: center;
  font-family: Arial;
  background: #111;
  color: #0f0;
}

#game {
  position: relative;
  width: 800px;
  height: 300px;
  margin: 20px auto;
  background: #222;
  overflow: hidden;
  border: 2px solid #0f0;
}

#player {
  position: absolute;
  width: 40px;
  height: 40px;
  background: cyan;
  bottom: 0;
  left: 50px;
  border-radius: 5px;
}

.obstacle {
  position: absolute;
  width: 40px;
  height: 40px;
  background: red;
  bottom: 0;
  right: 0;
}

#gameOver {
  position: absolute;
  width: 100%;
  text-align: center;
  top: 120px;
  font-size: 28px;
  color: #f00;
  display: none; /* hidden until game over */
}