JSFiddle - React, Tailwind, and code Playground

HTML

<html>
<head>


</head>
<body>
<a href="#" onmouseover="otkr()" onmouseout="zakr()">Меню</a>
<div id="svertmenu" style="display: none;">Это меню</div>
</body>
        <script>
var svertmenu = document.getElementById("svertmenu");
    function otkr(){

svertmenu.style.display = "block";
}
function zakr(){


svertmenu.style.display = "none";
}
    
</script>

</html>