Bootstrap 4 navigation tabs content not showing content on initial page load

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<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha/js/bootstrap.min.js"></script>
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha/css/bootstrap.min.css" rel="stylesheet"/>

<div class="container">
    <div class="card text-center">
        <div class="card-header">
            <ul class="nav nav-tabs card-header-tabs" id="tabs">
                <li class="nav-item">
                    <a class="active nav-link active" href="#post" data-toggle="tab">Post</a>
                </li>
                <li class="nav-item">
                    <a class="nav-link" href="#link" data-toggle="tab">Link</a>
                </li>
            </ul>
        </div>
        <div class="card-body">
            <div class="tab-content">
                <div class="tab-pane active" id="post">post</div>
                <div class="tab-pane" id="link">link</div>
            </div>
        </div>
    </div>
</div>