.custom-popup {
    display: none;
    position: fixed;
    top: 0; left: 0; right: 0; bottom: 0;
    background: rgba(0,0,0,0.7);
    z-index: 9999;
}
.popup-content {
    background: #fff;
    padding: 20px;
    max-width: 400px;
    margin: 100px auto;
    position: relative;
    border-radius: 8px;
}
.close-btn {
    position: absolute;
    top: 10px;
    right: 15px;
    font-size: 20px;
    cursor: pointer;
}
input, select, button {
    width: 100%;
    margin-bottom: 15px;
    padding: 10px;
}