/*  @media (min-width: 768px){
      #simpleModal .modal-dialog {
    width: 450px;
    margin: 100px auto 30px;
} 
     #simpleModal .modal-header {
    padding: 0px;
    border-bottom: 0px solid #e5e5e5;
}
#simpleModal .modal-header .close {
    margin-top: 3px;
    position: absolute;
    opacity: 1;
    z-index: 9;
    color: black;
    right: 10px;
}
  } */
@media (min-width: 768px){
#simpleModal1 .modal-dialog {
    width: 800px;
}
}
.modal-dialog .close {
    color: #000;
    float: right;
    font-size: 21px;
    font-weight: 600;
    line-height: 1;
    /* opacity: .2; */
    text-shadow: 0 1px 0 #fff;
}






<script type="text/javascript">
    window.onload = function () {
        OpenBootstrapPopup();
    };
    function OpenBootstrapPopup() {
        $("#simpleModal1").modal('show');
    }
</script>