<!-- Modal Tab: Calendar Overview -->
<div class="wpbs-tab wpbs-modal-tab" data-tab="insert-overview-calendar">

    <a href="<?php echo add_query_arg( array( 'page' => 'wpbs-calendars', 'subpage' => 'upgrade-to-premium' ), admin_url('admin.php') ); ?>" class="wpbs-wrap-upgrade-cta">
        <span class="wpbs-wrap-upgrade-cta-button">See details</span>
        <span class="wpbs-wrap-upgrade-cta-heading">The overview calendar only available in the premium version.</span>
    </a>

</div>