#goTopBtn {
    display: none; /* 初始時隱藏 */
    position: fixed; /* 固定在視窗上 */
    bottom: 20px;
    right: 20px;
    z-index: 99; /* 確保在其他元素之上 */
    border: none;
    outline: none;
    background-color: transparent; /* 透明背景 */
    cursor: pointer;
    width: 50px;
    height: 50px;
    padding: 5px; /* 調整內邊距以容納邊框 */
    border-radius: 50%; /* 圓形按鈕 */
    opacity: 0.7;
    transition: opacity 0.3s ease-in-out;
}

#goTopBtn:hover {
    opacity: 1;
}

.progress-ring {
    position: relative;
    width: 40px;
    height: 40px;
}

.progress-circle {
    display: block;
}

.progress-circle .background {
    /* 圓形背景 */
}

.progress-circle .indicator {
    /* 進度指示器 */
    stroke-linecap: round; /* 圓角 */
    transition: stroke-dashoffset 0.3s ease-out;
}

.arrow-up {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%) rotate(0deg);  /*垂直居中並向上旋轉 */
    width: 0;
    height: 0;
    border-left: 8px solid transparent;
    border-right: 8px solid transparent;
    border-bottom: 12px solid #000;  /*黑色箭頭 */
}