JSFiddle - React, Tailwind, and code Playground

HTML

<ul class='mainMenus'> 
                    <li onclick='showSubMenu(&quot;sm_item1&quot;)'>  
                        <div style='cursor:auto;font-size:40px; font-family:Segoe,Arial,sans-serif; color:White;padding-bottom:25px; padding-top:10px; padding-left:40px'><a href="#">Click here</a></div>
                          <ul class='subMenus' id='sm_item1'> 
                             <div style='width:1360px; height:685px;background:#CDDFF4; position:absolute; z-index:9999999999999999999; margin-left:0px; margin-top:-20px'>
                             <div style='height:580px'>
                                <div style='width:340px; height:480px; float:left; background:url()'>
                                    <div style='height:75px;width:340px;line-height:75px;text-align:left; font-weight:bold; color:#083047; font-size:13px'>
                                              


                                     </div>
                                    <div style='height:45px;width:340px;line-height:45px;text-align:left;padding-left:20px; font-weight:600; color:#083047; font-size:13px'>
                                        <a href='http://www.erhay.com/search/label/AB.M%C3%A1y%20t%C3%ADnh%20%C4%91i%E1%BB%87n%20tho%E1%BA%A1i' style='color:#083047'>Máy tính, điện thoại</a>
                                        </div>
                                        <div style='height:210px; width:340px; background:#72b9fa; padding-top:20px'>
                                        <div class='div-box1'>
                                            <ul>
                                                <li><a href='http://www.erhay.com/search/label/A1.H%C4%90H%20XP'>HĐH XP</a></li>
                                                <li><a href='http://www.erhay.com/search/label/A2.Windows%207'>HĐH Windows 7</a></li>
                                                <li><a href='http://www.erhay.com/search/label/A3.Windows%208'>HĐH Windows 8</a></li>
                   ...

CSS

<!-- Phần CSS cho Menu Click new -->
    #div-header .div-header
    {
    height:45px!important;
    width:340px!important;
    background:url();
    line-height:45px!important;
    text-align:left!important;
    padding-left:30px!important;
        margin-bottom:20px!important;
    }
    .div-subheader 
    {
    width:170px;
    line-height:20px;
    font:inherit;
    padding-left:40px;
    }
    .div-subheader a 
    {
    text-decoration:underline;
    font-size:12px;
    color:white;
    font-family:Verdana;
    }
    .div-header a
    {
    text-decoration:none;
    font-size:13px;
    color:white;
    font-family:Verdana;
    font-weight:bold;
    }
    .div-box1
    {
        height:170px; width:160px; float:left; list-style-type:none;padding-left:20px
    }
    .div-box2
    {
        height:170px; width:160px; float:left; 
    }
    .div-box1 ul li, .div-box2 ul li
    {
    list-style-type:none;
    text-decoration:none;
    padding-bottom: 15px;
    }
    .div-box1 ul li a, .div-box2 ul li a
    {
    text-decoration:none;
    color:white;
    font-family: inherit;
    }
    .div-box1 li a:hover, .div-box2 ul li a:hover
    {
    text-decoration:underline;
    }
    #menu-2{}


ul { 
margin: 0px 0px 0px 0px; 
padding: 0px 0px 0px 0px; 
list-style-type: none} 
  
.mainMenus li { 
position: relative} 
  
.subMenus { 
display: none; 
position: absolute; 
top: 20px; 
left: 0px;
}

JavaScript

window.onload=function() { 
 subMenusO = getElementsByClassName(document,'ul','subMenus'); 
} 
function showSubMenu(elemId) { 
 var dispStatus = (document.getElementById(elemId).style.display == 'block')? 'none' : 'block'; 
 for(var i=0; i < subMenusO.length; i=i+1) { 
     subMenusO[i].style.display = 'none'; 
    } 
    document.getElementById(elemId).style.display = dispStatus; 
} 
function getElementsByClassName(oElm, strTagName, strClassName){ 
    var arrElements = (strTagName == "*" && oElm.all)? oElm.all : oElm.getElementsByTagName(strTagName); 
    var arrReturnElements = new Array(); 
    strClassName = strClassName.replace(/\-/g, "\\-"); 
    var oRegExp = new RegExp("(^|\\s)" + strClassName + "(\\s|$)"); 
    var oElement; 
    for(var i=0; i<arrElements.length; i++) 
    { 
        oElement = arrElements[i]; 
        if(oRegExp.test(oElement.className)) 
        { 
            arrReturnElements.push(oElement); 
        } 
    } 
    return (arrReturnElements) 
        }