/* 提交訂單時的全畫面遮罩 */
#submitOverlay {
    position: fixed;
    inset: 0;
    display: none;
    align-items: center;
    justify-content: center;
    padding: 24px;
    background: rgba(0, 0, 0, .55);
    z-index: 99999;
}

#submitOverlay .box {
    max-width: 90vw;
    padding: 20px 28px;
    color: #fff;
    font-size: clamp(16px, 2.8vw, 22px);
    line-height: 1.5;
    text-align: center;
    background: rgba(0, 0, 0, .75);
    border-radius: 14px;
    box-shadow: 0 8px 30px rgba(0, 0, 0, .4);
}

#submitOverlay .spinner {
    width: 36px;
    height: 36px;
    margin: 0 auto 12px;
    border: 3px solid #fff;
    border-top-color: transparent;
    border-radius: 50%;
    animation: airport-spin 1s linear infinite;
}

@keyframes airport-spin {
    to { transform: rotate(360deg); }
}