body {
    margin: 0;
    overflow: hidden;
    background-color: #000;
}

#gameArea {
    position: relative;
    width: 100vw;
    height: 100vh;
    overflow: hidden;
    background: url('https://cdn.pixabay.com/photo/2016/08/14/14/58/pokemon-1593048_1280.jpg') no-repeat center center;
    background-size: cover;
}

#player {
    position: absolute;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%);
    width: 50px;
    height: 50px;
}

.bullet {
    position: absolute;
    width: 5px;
    height: 20px;
    background-color: #f00;
}

.obstacle {
    position: absolute;
    width: 50px;
    height: 50px;
}

#playerEnergy {
    position: absolute;
    top: 10px;
    left: 10px;
    color: #fff;
    font-size: 20px;
}

#gameTime {
    position: absolute;
    top: 10px;
    right: 10px;
    color: #fff;
    font-size: 20px;
}