newsupernova/vendor/magento/module-ui/view/base/web/templates/content/content.html

<!--
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
-->

<div html="content"
     css="$data.additionalClasses"
     visible="visible"></div>

<div data-role="spinner"
     class="admin__data-grid-loading-mask"
     visible="loading"
     if="showSpinner">
    <div class="spinner">
        <span repeat="8"/>
    </div>
</div>