body {
    margin: 0;
    overflow: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background-color: #add8e6; /* 薄い青 */
}

canvas {
    background-color: #ffffff; /* 白い雪 */
    border: 1px solid #ccc;
}