jellyfin-web/dashboard-ui/library.html

<div id="mediaLibraryPage" data-role="page" class="page type-interior mediaLibraryPage librarySectionPage withTabs" data-helpurl="https://github.com/MediaBrowser/Wiki/wiki/Library%20setup" data-require="scripts/medialibrarypage,scripts/taskbutton">

    <div data-role="content">
        <div class="content-primary">
            <div id="divVirtualFolders"></div>
            <br />
            <div>

                <paper-button raised class="btnRefresh"><iron-icon icon="refresh"></iron-icon><span>${ButtonScanLibrary}</span></paper-button>
                <progress max="100" min="0" style="display: inline-block; vertical-align: middle;" class="refreshProgress"></progress>
            </div>
        </div>
    </div>
</div>