.spinner {
    width: 50px;
    height: 50px;
    border: 5px solid #f3f3f3;
    border-radius: 50%;
    border-top: 5px solid #3498db;
    animation: spin 1s infinite linear;
    margin: 100px auto;
}
/* 로딩 스피너 애니메이션 효과 */
@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}
/* 로딩창 뒷배경 스타일링 */
.overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0,0,0,0.5);
    z-index: 999;
    display: flex;
    justify-content: center;
    align-items: center;
}