/* 배경 오버레이 스타일 */
.popup-backdrop {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: 999;
    /* 팝업보다 아래 */
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0.3s ease;
}

.popup-backdrop.visible {
    opacity: 1;
    visibility: visible;
}

.popup-backdrop.hidden {
    opacity: 0;
    visibility: hidden;
}