JSFiddle - React, Tailwind, and code Playground

HTML

<ul class="top-level-menu">

        <li><a href="hhh">hhh</a>


                    <ul class="second-level-menu">
                        
                        <li><a href="uu">uu</a>

                                <ul class="third-level-menu">
                                    
                                   <li><a href="gg">gg</a>
                                   </li>
                                   
                                </ul>

                        </li>

                    </ul>


        </li>
        
        
        <li>null</li>

</ul>

CSS

/* Menu Styles */

ul {display: inline;}

ul.third-level-menu::before {
content: '-';
position: relative;
left: -200px;
top: 10px;
}

ul::before {
content: '-';
position: relative;
left: 0px;
top: -20px;
}

.third-level-menu
{
    position: absolute;
    top: 0;
    right: -220px;
    width: 220px;
    list-style: none;
    padding: 0;
    margin: 0;

}

.third-level-menu > li
{
    height: 30px;
    background: #999999;
    display: none;
}
.third-level-menu > li:hover { background: #CCCCCC; }

.second-level-menu
{
    position: absolute;
    top: 30px;
    left: 0;
    width: 200px;
    list-style: none;
    padding: 0;
    margin: 0;
    
}

.second-level-menu > li
{
    position: relative;
    height: 30px;
    background: #999999;
    display: none;
}
.second-level-menu > li:hover { background: #CCCCCC; }

.top-level-menu
{
    list-style: none;
    padding: 0;
    margin: 0;
}

.top-level-menu > li
{
    position: relative;
    float: left;
    height: 30px;
    width: 100px;
    background: #999999;
}
.top-level-menu > li:hover { background: #CCCCCC; }

.top-level-menu li:hover > ul >li
{
    /* On hover, display the next level's menu */
    display: block;
}


/* Menu Link Styles */

.top-level-menu a /* Apply to all links inside the multi-level menu */
{
    font: bold 14px Arial, Helvetica, sans-serif;
    color: #FFFFFF;
    text-decoration: none;
    padding: 0 0 0 10px;

    /* Make the link cover the entire list item-container */
    display: block;
    line-height: 30px;
}
.top-level-menu a:hover { color: #000000; }