<div class="uk-section uk-height-viewport uk-flex uk-flex-middle">
    <div class="uk-container">

        <style>
            .test { height: 60px; }
        </style>

        <div class="test">
            <div class="uk-tooltip uk-tooltip-top-center uk-display-inline-block uk-margin-remove">Tooltip</div>
        </div>

        <button class="uk-button uk-button-default" title="Hello World" uk-tooltip>Top</button>

    </div>
</div>