var cont_slc = 0;

                                                    function open_select(idx) {
                                                        var idx1 = idx.getAttribute('data-n-select');
                                                        var ul_cont_li = document.querySelectorAll("[data-indx-select='" + idx1 + "'] .cont_select_int > li");
                                                        var hg = 0;
                                                        var slect_open = document.querySelectorAll("[data-indx-select='" + idx1 + "']")[0].getAttribute(
                                                            'data-selec-open');
                                                        var slect_element_open = document.querySelectorAll("[data-indx-select='" + idx1 + "'] select")[0];
                                                        if (Mobile_ || FirfoxMobile) {
                                                            if (window.document.createEvent) { // All
                                                                var evt = window.document.createEvent("MouseEvents");
                                                                evt.initMouseEvent("mousedown", false, true, window, 0, 0, 0, 0, 0, false, false, false, false,
                                                                    0,
                                                                    null);
                                                                slect_element_open.dispatchEvent(evt);
                                                            } else if (slect_element_open.fireEvent) { // IE
                                                                slect_element_open.fireEvent("onmousedown");
                                                            }
                                                        } else {
                                            
                                            
                                                            for (var i = 0; i < ul_cont_li.length; i++) {
                                                                hg += ul_cont_li[i].offsetHeight;
                                                            };
                                                            if (slect_open == 'false') {
                                                                document.querySelectorAll("[data-indx-select='" + idx1 + "']")[0].setAttribute(
                                                                    'data-selec-open',
                                                                    'true');
                                                                document.querySelectorAll("[data-indx-select='" + idx1 + "'] > .cont_list_select_mate > ul")[0]
                                                                    .style.height = hg + "px";
                                                                document.querySelectorAll("[data-indx-select='" + idx1 + "'] > .icon_select_mate")[0].style
                                                                    .transform = 'rotate(180deg)';
                                                            } else {
                                                                document.querySelectorAll("[data-indx-select='" + idx1 + "']")[0].setAttribute(
                                                                    'data-selec-open',
                                                                    'false');
                                                                document.querySelectorAll("[data-indx-select='" + idx1 + "'] > .icon_select_mate")[0].style
                                                                    .transform = 'rotate(0deg)';
                                                                document.querySelectorAll("[data-indx-select='" + idx1 + "'] > .cont_list_select_mate > ul")[0]
                                                                    .style.height = "0px";
                                                            }
                                                        }
                                            
                                                    } // fin function open_select
            
         

<html lang="en">

<head>


 
 


</head>
<body>





    

    

        
 Hello world 
        
 Lorem ipsum dolor sit amet,   ut labore et   
 
        
 nostrud exercitation ullamco laboris nisi ut 
        

        Custom 
    
    

    


</div>  
    
   
     

</body>
</html>  
    
 

                                    body{
                                    background:white;
                                    font-size:16px;
                                    color:black ;
                                    line-height:1.3px ;
                                    }
                                    h1 {
                                    font-size:2rem;
                                    line-height:1.3
                                    }
                                    .button {
                                    background:#f43453;
                                    color:white;
                                    font-size:12px;
                                    padding: 20px 10px
                                    }