body {
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    /* 背景圖片設定 */
    background: url('../background.jpg') no-repeat center center fixed;
    background-size: cover;
    font-family: 'Microsoft JhengHei', sans-serif;
}

.container {
    text-align: center;
    background: rgba(255, 255, 255, 0.8);
    padding: 30px;
    border-radius: 20px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.3);
}

#bamboo-tube {
    width: 200px;
    cursor: pointer;
    transition: transform 0.1s;
}

/* 搖晃動畫 */
.shake {
    animation: shake-animation 0.5s infinite;
}

@keyframes shake-animation {
    0% { transform: rotate(0deg); }
    25% { transform: rotate(10deg); }
    50% { transform: rotate(0deg); }
    75% { transform: rotate(-10deg); }
    100% { transform: rotate(0deg); }
}

.hidden {
    display: none;
}

.fortune-card {
    margin-top: 20px;
    padding: 20px;
    border: 5px double #8b0000;
    background-color: #fff5f5;
    animation: fadeIn 1s;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

button {
    margin-top: 15px;
    padding: 10px 20px;
    background: #8b0000;
    color: white;
    border: none;
    cursor: pointer;
    border-radius: 5px;
}

/* 返回按鈕：左上角固定 */
.back-btn {
    position: absolute;
    top: 20px;
    left: 20px;
    padding: 8px 15px;
    background: rgba(0, 0, 0, 0.5);
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
}