<div class="uk-section uk-height-viewport">

    <style>
        .test { height: 2500px; }
    </style>

    <div class="uk-container uk-container-small test">

        <div id="viewport" class="uk-height-viewport test-border">
            <div class="uk-card uk-card-primary uk-card-body uk-text-center" uk-sticky="offset: -250; top: 250; animation: uk-animation-slide-top">Slide with 250px offset</div>
        </div>

    </div>

</div>