body {
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background-image: url('grass.jpg'); /* 绿色草坪背景 */
    background-size: cover;
}

#game-container {
    position: relative;
    width: 800px;
    height: 600px;
    border: 1px solid #333;
    background-color: rgba(255, 255, 255, 0.5);
}

#circle {
    position: absolute;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background-color: blue;
}

.square {
    position: absolute;
    width: 20px;
    height: 20px;
    background-color: red;
}

#timer {
    position: absolute;
    top: 10px;
    left: 10px;
    color: white;
    background-color: rgba(0, 0, 0, 0.7);
    padding: 5px;
    border-radius: 5px;
}

#level {
    position: absolute;
    top: 10px;
    right: 10px;
    color: white;
    background-color: rgba(0, 0, 0, 0.7);
    padding: 5px;
    border-radius: 5px;
}

#congratulations {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 36px;
    color: green;
    z-index: 10;
}

#level-message {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 24px;
    color: white;
    background-color: rgba(0, 0, 0, 0.7);
    padding: 20px;
    border-radius: 10px;
    z-index: 10;
}