def thumbnail(tag: :div, **options, &block)
      content_tag(tag, nil, merge_predef_class('thumbnail', options)) do
        capture(&block)
      end
    end
def thumbnail(tag: :div, **options, &block)
      content_tag(tag, nil, merge_predef_class('thumbnail', options)) do
        capture(&block)
      end
    end
Public: Thumbnail element.

 tag     - Symbol or String. HTML tag of thumbnail. ( default: :div )
 options - Options can be accepted by the tag specified.