JSFiddle - React, Tailwind, and code Playground

HTML

<div id="wbw">
    <a class="wh" onmouseover="showIframe()" onmouseout="hideIframe()"></a>
    <div id="ta_widget_box" onmouseover="showIframe()" onmouseout="hideIframe()"></div>
    <script language="Javascript" src="http://reviews.treatmentabroad.com/js/widget.js"></script>
    <script language="Javascript">
        var intervalId;
        var intervalDuration = 500;

        function showIframe(){
            clearTimeout(intervalId);
            document.getElementById('ta_widget_box').style.display='block';
        }

        function hideIframe(){
            
            intervalId = setTimeout("hideIframeCallback()", intervalDuration);
        }

        function hideIframeCallback(){
  
            document.getElementById('ta_widget_box').style.display='none';
        }
        
        init_widget_rnr('278237/es','ta_widget_box');
    </script>
</div>

CSS

/* Widget - iframe na hlavni strance */
#ta_widget_box, #wbw {
    position: absolute;
    left: 20px;
    top: 20px;
    height: 156px;
    width: 262px;
}

#wbw {
    z-index: 10000;
}

#ta_widget_box {
    position: absolute;
    top: 0;
    left: 0;
    z-index: 900;
    display: none;
}

#ta_widget_box iframe {
    border-radius: 10px;
    -webkit-box-shadow:  0px 2px 5px -1px #333;
    box-shadow:  0px 2px 5px -1px #333;
    height: 156px;
    position: relative;
    z-index: 1000;
}

#ta_widget_box:hover {
    display: block;
}

#wbw a.wh {
    width: 261px;
    height: 55px;
    display: block;
    background: url('http://durian.newlogic.cz/img/widget/bg.png') no-repeat left top;
    cursor: pointer;
    border: 0;
    border-radius: 10px 10px 10px 15px;
    -webkit-box-shadow:  0px 2px 5px -1px #333;
    box-shadow:  0px 2px 5px -1px #333;
    position: relative;
    z-index: 2000;
}

#wbw a.wh:hover {
    box-shadow: 0;
    -webkit-box-shadow: 0;
}
/*
#wbw a.wh:hover + #ta_widget_box {
    display: block;
}*/