JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    <img src="http://lorempixel.com/300/200" />
    <img src="http://cdn-img.easyicon.cn/png/270/27093.png" class="watermark" />
    
</div>

CSS

div {
    position: relative;
    display: inline-block;
}

div:hover img.watermark {
    display: block;
}

img.watermark {
    position: absolute;
    bottom: 0;
    right: 0;
    opacity: .6;
    display: none;
}