/* ===== 共用基底 ===== */
#page-watermark {
    position: fixed;
    inset: 0;
    z-index: 9999;
    pointer-events: none; /* 不擋操作 */
    user-select: none;
}

    /* ===== 模式 A：單一大 SVG 置中 ===== */
    #page-watermark.mode-center {
        display: flex;
        align-items: center;
        justify-content: center;
    }

    /* ===== 模式 B：密集鋪滿 ===== */
    #page-watermark.mode-tile {
        background-repeat: repeat;
        background-position: 0 0;
        background-size: 300px 200px; /* 密集度：越小越密 */
    }