/* ==================== 閱讀進度按鈕（固定右下角） ==================== */
.progress-btn-wrapper {
    position: fixed;
    right: 20px;
    bottom: 20px;
    width: 55px;
    height: 55px;
    z-index: 9999;
    cursor: pointer;
    opacity: 0;
    transform: translateX(100px);
    transition: all 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

.progress-btn-wrapper.show {
    opacity: 1;
    transform: translateX(0);
}

/* SVG 進度環覆蓋整個 wrapper */
.progress-btn-wrapper svg {
    position: absolute;
    top: 0;
    left: 0;
    width: 55px;
    height: 55px;
    transform: rotate(-90deg); /* 從12點鐘方向開始繞 */
}

/* 灰色軌道 */
.progress-track {
    fill: none;
    stroke: rgba(255, 255, 255, 0.3);
    stroke-width: 3;
}

/* 白色進度線 */
.progress-ring {
    fill: none;
    stroke: #ffffff;
    stroke-width: 3;
    stroke-linecap: round;
    transition: stroke-dashoffset 0.1s linear;
}

/* 中心圓形圖示 */
.progress-btn-inner {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 43px;
    height: 43px;
    background: #3fb1e7;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 15px rgba(63, 177, 231, 0.4);
    transition: all 0.3s ease;
    z-index: 2;
}

.progress-btn-inner img {
    width: 24px;
    height: 24px;
    object-fit: contain;
}

.progress-btn-wrapper:hover .progress-btn-inner {
    transform: translate(-50%, -50%) scale(1.08);
    box-shadow: 0 6px 20px rgba(63, 177, 231, 0.6);
}

/* ==================== 手機版適配 ==================== */
@media (max-width: 768px) {
    .progress-btn-wrapper {
        right: 15px;
        bottom: 85px; /* 往上移，避開 App Bar */
        width: 50px;
        height: 50px;
    }

    .progress-btn-wrapper svg {
        width: 50px;
        height: 50px;
    }

    .progress-btn-inner {
        width: 38px;
        height: 38px;
    }

    .progress-btn-inner img {
        width: 20px;
        height: 20px;
    }
}

@media (max-width: 480px) {
    .progress-btn-wrapper {
        width: 45px;
        height: 45px;
    }

    .progress-btn-wrapper svg {
        width: 45px;
        height: 45px;
    }

    .progress-btn-inner {
        width: 34px;
        height: 34px;
    }

    .progress-btn-inner img {
        width: 18px;
        height: 18px;
    }
}