* {
    margin:0;
    padding:0;
    box-sizing: border-box;
}

#canvas1{
    border: 5px solid black;
    position: absolute;
    top:50%;
    left:50%;
    transform: translate(-50%,-50%);
    max-width: 100%;
    max-height: 100%;
}

#bg, #android, #virus, #green_platform, #blue_platform, #brown_platform, #white_platform, #bullet{
    display: none;
}