#message-bg { 
    position:fixed;
    padding:20px; 
    background:rgb(0,0,0,0.5); 
    width:100%;  
    z-index:4; 
    bottom:0; 
    left:0;
    text-align:center;
  }
  #message { 
    width:90%; 
    max-width:500px;
    margin:0 auto;
    padding:20px;
    background:white; 
    z-index:5; 
    border:1px solid darkgrey;
    text-align:left; 
  }
  #message>input {
    display:block;
    margin:0 auto;
    margin-top:16px;
    padding:12px;
    cursor:pointer;
  }