.garden {
    position: relative;
    width: 200px;
    height: 200px;
    border: 5px solid #ccc;
    border-radius: 10px;
}

.ball {
    position: absolute;
    top: 90px;
    left: 90px;
    width: 20px;
    height: 20px;
    background: green;
    border-radius: 100%;
}

#canvas {
    border: 1px solid black;
}