#field {
    background-color: #4CAF50;
    position: relative;
    overflow: hidden;
    width: 100%;
    max-width: 100%;
    max-height: 100%;
    aspect-ratio: 100 / 75;
    flex-shrink: 1;
    transform-origin: center;
}

.ball {
    width: 8px;
    height: 14px;
    background-color: #ffffff;
    border-radius: 50% / 60%;
    border: 1px solid #000000;
}