JSFiddle - React, Tailwind, and code Playground

HTML

<div class="MENU" unselectable="on" style="background-color:rgb(181, 230, 29);width:216px;height:auto;position:relative;top:auto;right:auto;z-index:inherit;bottom:auto">
								<a id="bt4" unselectable="on" style="clip:rect(200px, auto, auto, auto)">
								<h3>Experimentation</h3></a>
								<div unselectable="on" id="bloc4" class="bloc">
									<ul id="menu-vertical">
										<li><a href="#">Programme</a></li>
										<li class="dropdown-submenu"><a href="#">
                                            Protocoles<span class="caret"></span></a>
											<ul class="dropdown-menu">
												<li><a>Carotte</a></li>
												<li><a>Laitue</a></li>
												<li><a>Chou-fleur</a></li>
												<li><a>Chicorée</a></li>
												<li><a>Bettewrave</a></li>
												<li><a>Haricots</a></li>
												<li><a>Multi-espèces</a></li>
												<li><a>Autres</a></li>
											</ul>
										</li>
										<li class="dropdown-submenu"><a href="#">
										Compte rendu<span class="caret"></span></a>
											<ul class="dropdown-menu">
												<li><a>Carotte</a></li>
												<li><a>Laitue</a></li>
												<li><a>Chou-fleur</a></li>
												<li><a>Chicorée</a></li>
												<li><a>Betterave</a></li>
												<li><a>Haricots</a></li>
												<li><a>Multi-espèces</a></li>
												<li><a>Autres</a></li>
											</ul>
										</li>
										<li class="dropdown-submenu"><a href="#">
										Historique et bases de données<span class="caret"></span></a>
											<ul class="dropdown-menu">
												<li class="dropdown-submenu"><a href="#">
												Réunion expe<span class="caret"></span></a>
													<ul class="dropdown-menu">
														<li><a>Vilmorin</a></li>
														<li><a>FNAMS</a></li>
														<li><a>Projets 
														multi-partenaires</a></li>
													</ul>
												</li>
												<li><a>Historique</a></li>
												<li><a>Bases de...

CSS

.MENU a, .item_list a
{
color:#0066FF
}

body li /*:nth-child(odd)*/
{
	margin-bottom:3px;
}
.ms-dlgContent

{  
    overflow:scroll;   
}

.MENU:after {
    content: "";
    display: inline;
    height: 0px;
    clear: both;
}

#banniere_site
{
	width: 100%;
	margin-left: 5px;
	border-radius:25px;
}
.ms-dlgFrame

{

    overflow:hidden;

}

.MENU 
{
	border-radius: 15px;
	border: 2px groove #0C0;
}

#item_list_1 a:hover, #item_list_2 a:hover {
	padding-left:10px;
	text-decoration:none;
	font-size: 125%;
	
}

#item_list_1:hover, #item_list_2:hover 
{
	box-shadow: 0px 0px 20px #65ff65;
}

.MENU ul:first-child {
	width: 195px;
}
.caret {
display: inline;
width: 0;
height: 0;
margin-left: 2px;
vertical-align: middle;
border-top: 4px solid;
border-right: 4px solid transparent;
border-left: 4px solid transparent;
position:relative;
right:0px;
top:6px;
float:right;
}

#prez-title span.caret
{
	float: none;
	top: 10px;
	left: 3px;
}
#item_list_1
{
	width:226px;
	position:relative;
	border:medium outset #00FF00;
	background-color:#66FF66;
	height:auto;
	right:auto;
	bottom:auto;
	left:25px;
}
#item_list_1 ul
{
	list-style:none;left:-30px;
}
#item_list_2
{
	width:226px;
	position:relative;
	top:20%;
	left:25px;
	border:medium outset #00FF00;
	background-color:#66FF66;
	height:auto;
	right:auto;
	bottom:auto
}
#item_list_2 ul
{
	list-style:none;left:-30px;
}

.bloc
{
	padding:8px;
	border-style:none;
	background-color:rgb(204, 255, 102);
	color:#0066FF;
	position:relative;
	display:block;
	height:auto;
	border-bottom-right-radius: 15px;
	border-bottom-left-radius: 15px;
	left:0px;top:0px
	
}
#bloc5, #bloc6
{
	display:none;
		
}
.MENU:hover
{
	box-shadow: 0px 0px 20px #b5e51d;

}

.MENU img
{
	border-bottom-right-radius: 15px;
	border-bottom-left-radius: 15px;
	border-top-left-radius: 15px;
	border-top-right-radius: 15px;
}
.dropdown-menu {
  transition: 0.5s ease-in-out;
  -webtkit-transition:2s ease-in-out;
  opacity:1;
  -moz-transition: 1s opacity...

JavaScript

/*
$('#menu-vertical').each(function(){
    $("a").attr("href") = "http://www.google.com";
});
*/
$(".dropdown-menu").hide();
$(".dropdown-submenu").css("border", "1px solid red");
$('.dropdown-submenu').on('click', function(){
    //alert('clicked');
    $(this).find(".dropdown-menu:first").toggle();
});