JSFiddle - React, Tailwind, and code Playground

HTML

<ul class="navigation" >
 <li class="inset_header1 " id="inset_header1" onClick="click_header_inset(1);"><a href="#"><div class="icon"><i class="fa fa-home"></i></div>пункт 1</a></li>
 <li class="inset_header2 " id="inset_header2" onClick="click_header_inset(2);"><a href="#"><div class="icon"><i class="fa fa-pencil"></i></div>пункт 2</a></li> 
 <li class="inset_header3 " id="inset_header3" onClick="click_header_inset(3);"><a href="#"><div class="icon"><i class="fa fa-picture-o"></i></div>пункт 3</a></li>
 <li class="inset_header4 " id="inset_header4" onClick="click_header_inset(4);"><a href="#"><div class="icon"><i class="fa fa-user"></i></div>пункт 4</a></li> 
 <li class="inset_header5 " id="inset_header5" onClick="click_header_inset(5);"><a href="#"><div class="icon"><i class="fa fa-envelope-o"></i></div>пункт 5</a></li>
 </ul>

<div class="block_inset">

 <div class="inset_num" id="inset_num1">
 <div class="inset_content">
 <h2>Блок пункта 1</h2>     
 </div>
 </div>
 <div class="inset_num" id="inset_num2">
 <div class="inset_content">
 <h2>Блок пункта 2</h2> 
 </div> 
 </div>
 <div class="inset_num" id="inset_num3">
 <div class="inset_content">
 <h2>Блок пункта 3</h2>
 </div>
 </div>


 <div class="inset_num" id="inset_num4">
 <div class="inset_content">
 <h2>Блок пункта 4</h2>
 </div>
 </div> 
 <div class="inset_num" id="inset_num5">
 <div class="inset_content">
 <h2>Блок пункта 5</h2>
 </div>
 </div>  
    
<div class="reltr" id="inse_num">A</div>
   
 </div>

CSS

.block_inset { 
 position:absolute;
 top:0px;
 bottom:0px; 
 left:113px;
 width:340px; 
 height:110%;
 overflow-x:hidden; 
 }

.inset_content { 
 position:relative;
 margin:0px; 
 padding:0px;
 width:100%; 
 height:100%;
 color:#fff;   
 background-color: rgba(0, 0, 0, 0.8); 
 overflow-y:auto;
}
.inset_num { 
 position:absolute; 
 top:0px;
 bottom:0px; 
 width:300px; 
 height:100%;
 left:-300px;
 z-index:3; 
}
.reltr{
 z-index:2;
 left:0px;   
 width: 40px;
 height: 100%; 
 position: absolute;
 background:#b5b5b5;
 top:0; 
}

JavaScript

function setCookie(name, value, days) {
 if (days) {
 var date = new Date();
 date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
 var expires = "; expires=" + date.toGMTString();
 }
 else var expires = "";
 document.cookie = name + "=" + value + expires + "; path=/";
}
function getCookie(name) {
 var nameEQ = name + "=";
 var ca = document.cookie.split(';');
 for (var i = 0; i < ca.length; i++) {
 var c = ca[i];
 while (c.charAt(0) == ' ') c = c.substring(1, c.length);
 if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length, c.length);
 }
 return null;
}
function eraseCookie(name) {
 setCookie(name, "", -1);
};
num_inset_motor=0;
flag_inset_motor=0;
time_pause_motor=1;
delta_x=10;
set_motor=false;
id_settimeout=0;
open_inset_num=0;
next_open_num=0;
width_header=0;

var blockStateCookie = +getCookie('blockState');
blockStateCookie && click_header_inset(blockStateCookie)



function click_header_inset(n_inset) {


       setCookie('blockState', 0, 1000);
   if (!set_motor)
     {
      next_open_num=0;
      if (open_inset_num==0)
        { setCookie('blockState', n_inset, 1000);
         num_inset_motor=n_inset;
         flag_inset_motor=1;
         set_motor=true;
         motor_inset();
        }
       else
         {
          if (n_inset!=open_inset_num) {
           next_open_num=n_inset; setCookie('blockState', n_inset, 1000);
          }
          num_inset_motor=open_inset_num;
          flag_inset_motor=-1;
          set_motor=true;
          motor_inset();

         }
     }
    else
      {
       clearTimeout(id_settimeout);
       if (n_inset==num_inset_motor)
         {
          flag_inset_motor*=-1;
          motor_inset();
         }
        else
          {
           next_open_num=n_inset;
           if (flag_inset_motor>0)
             {
              flag_inset_motor=-1;

             }
           motor_inset();
          }
      }
  }

function motor_inset()
  {
   if (num_inset_motor==0) return;
   if (flag_inset_motor==0)...