https://coliss.com/articles/build-websites/operation/css/css-ribbon-shapes.html

html <div id="select" class="bl_selectBlock"> <div class="el_searchResult"> <span class="el_searchResult_nume js_numerator"></span>件／全<span class="el_searchResult_deno js_denominator"></span>件 </div> <div class="bl_selectBlock_wrapper"> <div class="bl_selectBlock_wrapper_wrapper"> </div></div></div>

https://qiita.com/watarunto006/items/1375bc7e6312f65d635b