JSFiddle - React, Tailwind, and code Playground

HTML

<header>
		<ul>
			<li>
				<a href="#">Menu Option</a>
                <div class="previewImg">Preview Image Here</div>
			</li>
			<li>
				<a href="#">Menu Option</a>
				<div class="previewImg">Preview Image Here</div>
			</li>
		</ul>
	</header>

CSS

header {
  position: fixed;
  width: 100%;
  background-color: #336699;
  
}
header li {
  display: inline-block;
  position: relative;
}
header li:hover .previewImg {
  display: block;
}
header .previewImg {
  position: absolute;
  display: none;
}
header a {
  display: block;
  padding: 10px;
  background-color: #ccc;
}
.previewImg
{
    height: 100px;
    width: 75px;
    background: orange;
    z-index: 999;
}