.modalDialog {
    display:none;
    position: fixed;
    font-family: Arial, Helvetica, sans-serif;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    background: rgba(0, 0, 0, 0.8);
    z-index: 99999;
    /*
    opacity:0;
    -webkit-transition: opacity 400ms ease-in;
    -moz-transition: opacity 400ms ease-in;
    transition: opacity 400ms ease-in;
    */
}

.modalDialog > div {
    width: 400px;    
    position: relative;
    margin: 10% auto;
    padding: 5px 20px 13px 20px;
    border-radius: 10px;
    background: #fff;   
}

@media screen and (max-width: 420px) {      
    .modalDialog > div {
        width: 260px;
    }
}