.sdn-modal {
    position: fixed;
    z-index: 9999;
    left: 0; top: 0;
    width: 100%; height: 100%;
    background: rgba(0,0,0,0.5);
    display: flex; align-items: center; justify-content: center;
}
.sdn-modal-content {
    background: #fff;
    padding: 30px;
    max-width: 500px;
    border-radius: 8px;
    text-align: center;
}
.sdn-modal-content h2 {
    margin-top: 0;
}
.sdn-modal-content button {
    margin-top: 20px;
    padding: 10px 20px;
}