Cards have a transparent background

Created by: DDynamic

When using the latest v4 Alpha 1, cards do not have a white background as expected (like in v3) when placed on a jumbotron or other image.

HTML Code:

<div class="jumbotron">
    <div class="container-fluid col-xs-12 col-sm-8">
        ...
    </div>
    <div class="col-sm-4">
        <div class="card card-default">
            <div class="card-header">Featured</div>
            <div class="card-block">
                Hey
            </div>
        </div>
    </div>
</div>

Custom Jumbotron CSS (Written in style tags)

.jumbotron {
position: fixed;
background: #000 url("https://static.mywebsite.com/photos/image.jpg") center center;
top: 0;
left: 0;
min-width: 100%;
min-height: 100%;
}

Thank you for your time and amazing software!