<div class="uk-section uk-section-default">
    <div class="uk-container uk-container-small" style="height: 2000px;">

        <div id="viewport" class="test-border" style="height: 600px; border: 1px dashed rgba(0,0,0,0.2);">
            <div class="uk-card uk-card-primary uk-card-body uk-text-center" uk-sticky="top: 250; bottom: #viewport; animation: uk-animation-slide-top">Slide with 250px offset</div>
        </div>

    </div>
</div>