body {
    background-image: url("https://i.ytimg.com/vi/X2cl6_DVpFI/maxresdefault.jpg");
    background-size: 40%;
    display: flex;
    align-items: center;
    flex-direction: column;
    height: 100vh;
    margin: 0;
    background-color: #f0f0f0;
}

button{
    background: transparent;
    border: none;   
    width: 70%;
    height: 100%;
}

#gameCanvas {
    background-image: url("https://thumbs.dreamstime.com/z/ciel-de-midi-21765100.jpg");
    border: 2px solid #000;
    width: 600px;
    height: 950px;
}