.pw_prompt {
    position:fixed;
    left: 50%;
    top:50%;
    margin-left:-100px;
    padding:15px;
    width:200px;
    border:1px solid black;
    background-color: #fff;
    text-align: center;
}
.pw_prompt label {
    display:block; 
    margin-bottom:5px;
}
.pw_prompt input {
    margin-bottom:10px;
}