JSFiddle - React, Tailwind, and code Playground
HTML
<div class="primary-menu-container"><ul id="primary-menu-list" class="menu-wrapper"><li id="menu-item-21" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-21"><a href="">foo A</a></li>
<li id="menu-item-31" class="menu-item menu-item-type-post_type menu-item-object-page current-menu-ancestor current-menu-parent current_page_parent current_page_ancestor menu-item-has-children menu-item-31"><a href="">foo b</a>
<ul class="sub-menu">
<li id="menu-item-22" class="menu-item menu-item-type-taxonomy menu-item-object-category menu-item-22"><a href="">foo bb</a></li>
</ul>
</li>
<li id="menu-item-44" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-44"><a href="">foo c</a></li>
</ul></div>
CSS
#site-navigation {
position: relative;
float:right;
margin-top:-50px;
}
.menu-item-type-taxonomy {
list-style: none;
}
a.menu-wrapper {
text-decoration: none;
}
ul.menu-wrapper {
list-style-type: none;
display:flex;
list-style:none;
}
li.menu-item {
list-style:none;
margin:10px;
}
a.menu-wrapper{
color:#000000;
}
ul.menu-wrapper li >ul {
display: none;
}
ul.menu-wrapper li:hover >ul {
display:block;
}