Centering log in grid in my container?

Question

I have tried different kinds of approach to center my log-in. I want it to be vertically and horizontally centered in my container. Would appreciate any help! Can someone give me some good idea?

<div class="container login">
    <div class="col-md-4 login-centered">
        <div class="panel panel-default">
            <div class="panel-heading"><h3 class="panel-title"><strong style="color:white">Sign in </strong></h3></div>
            <div class="panel-body">
                <section role="form">
                    @using (Html.BeginForm()
                    {
                        @Html.AntiForgeryToken()
                        @Html.ValidationSummary()

                        <div class="form-group" style="display:block;margin:auto;">
                            <label>Username</label>
                            @Html.TextBoxFor()
                            @Html.ValidationMessageFor()
                        </div>

                        <div class="form-group" style="display:block;margin:auto;margin-top:6px;">
                            <label >Password</label>
                            @Html.PasswordFor()
                            @Html.ValidationMessageFor( )
                        </div>
                            <input type="submit" value="Log in" class="pull-right btn-sm btn-default" />
                    }
                </section>
            </div>
        </div>
    </div>
</div>

This is my css:

.login-centered {
    display:block;
    margin-left:auto;
    margin-right:auto;
}
.panel-heading {
    background-color: #2190b6!important;
}
.btn-default {
    background-color: #2190b6 !important;
    border: 1px solid #2190b6 !important;
    color: #FFF!important;
    margin-top: 10px;
}
.btn-default:hover,  .btn-default:active:focus{
    background-color: #2190b6 !important;
    border: 1px solid #2190b6 !important;
    color: #FFF!important;
}

Answer 1

The following CSS code should do the job !!

.login-centered {
    top: 50%;
    left: 50%;
    transform: translateX(-50%) translateY(-50%);
    position: absolute;
}