<수정하던 소스>

            <?php if($content->thumbnail_file):?>
            <div class="kboard-attach">
                <div class="kboard-attach-title"><?php echo __('Thumbnail', 'kboard')?></div>
                <button type="button" class="kboard-button-action kboard-button-download" onclick="" title="<?php echo sprintf(__('Download %s', 'kboard'), $content->thumbnail_name )?>">
                    <?php echo $content->thumbnail_name?>
                </button>
            </div>
            <?php endif?>