body{ text-align:center}
.content{
    margin-left: auto;
    margin-right: auto;
}
.content.modal-content{
    margin-left: auto;
    margin-right: auto;
}
.form-horizontal{
    max-width: 500px;
    margin-left: auto;
    margin-right: auto;
    padding: 20px;
}
.modal.fade.in{
    top:20%;
}
.modal-dialog{
    margin-left: auto;
    margin-right: auto;
    max-width: 300px;
}