JSFiddle - React, Tailwind, and code Playground

HTML

<div class="dropmenu">
 <ul id="nav">
  <li class="matches"><a href="#">Main Menu</a>
   <ul>    
    <li><a href="#" id="leagueSelect" data-comp="1">Menu 1</a></li>
    <li><a href="#" id="leagueSelect" data-comp="2">Menu 2</a></li>
    <li><a href="#" id="leagueSelect" data-comp="3">Menu 3</a></li>
    <li><a href="#" id="leagueSelect" data-comp="4">Menu 4</a></li>
   </ul>
  </li>

  <li class="matches"><a href="#">Sub Menu</a>
   <ul class="fixture-list">
    <div class="fixtures">
                  <li><a href="#">1</a></li>
                  <li><a href="#">2</a></li>
                  <li><a href="#">3</a></li>
                  <li><a href="#">4</a></li>     
    </div>
    
   </ul>
   
  </li>

 </ul>

</div>

CSS

/* remove the list style */
	#nav {
		margin:0 auto; 
		padding:0; 
		list-style:none;
		position:absolute;
		z-index:10000;
	}	
	
		/* make the LI display inline */
		/* it's position relative so that position absolute */
		/* can be used in submenu */
		#nav li {
			float:left; 
			display:block; 
			background:#ccc; 
			position:relative;
			z-index:500; 
			margin:0 1px;
			text-align:center;
		}
		
		#nav li.title {
            background:#666666;
			width:85px;
			font-size:10px;
		}
		
		#nav li.matches {
			width:100px;
			height:30px;
		}
		
		#nav li.matches a:hover {
			height:25px;
		}
				
		/* this is the parent menu */
		#nav li a {
			font-size:12px;
	        color:#fff;
			display:block; 
			padding:8px 5px 0 5px; 
			height:22px; 
			text-decoration:none; 			
		}
		
		.dropmenu #nav li a {
			font-family: Candara, Calibri, Segoe, "Segoe UI", Optima, Arial, sans-serif;
			font-size:12px;			
			color:#fff;
			padding-top:6px;
			text-align:left;
			height:25px;
		}
		
		.dropmenu #nav li.matches{
			width:107px;
			text-align:left;
			background-color:#797979;
			height:31px
		}
		
		.dropmenu #nav li.matches img{
			float:left;
			margin-left:8px;
			margin-right:8px;
			margin-top:8px;
		}
		
		.dropmenu #nav li.matches img.matchesMenu{
			margin-right:15px;
		}

		#nav li a:hover {
			background-color:#666;
			color:#fff;	
		
		}

		#nav li.matches a:hover {
			color:#fff;
			height:
		}
		
		#nav li.title a:hover {
			background-color:#666;
			color:#ccc;
		}

		/* you can make a different style for default selected value */
		#nav a.selected {
			color:#f00;
		}
	
		/* submenu, it's hidden by default */
		#nav ul {
			position:absolute; 
			left:0; 
			display:none; 
			margin:0 0 0 -1px; 
			padding:0; 
			list-style:none;	
		}
		
		#nav ul li {
			width:107px; 
			float:left; 
			border-top:1px solid #fff;
			padding-left:0px;
		}
		
		/* display block will make the link fill the whole area of LI */
		#nav ul a  {
			display:block; ...

JavaScript

$(function(){
	
	$('#nav li').hover(
		function () {
			//show its submenu
			$('ul', this).stop().slideDown(100);

		}, 
		function () {
			//hide its submenu
			$('ul', this).stop().slideUp(10);
			//$('ul', this).stop().hide();
		}
	);
    
    $('a#leagueSelect').hover(function(){
 
         $('ul.fixture-list').slideDown(50);		
        
	});

    
});