html,body{
    height: 100%;
    margin: 0px;
    padding: 0px;
}
.container {
    display: flex;
    height: 100%;
    margin: 0 auto;
    justify-content: center;
    align-items: center;
}
.child {
    display: table-cell;
    vertical-align: middle;
}
.child #loginForm{
    padding: 10px;
    width: 350px;
}