JSFiddle - React, Tailwind, and code Playground

HTML

<div>    
    <img src="http://placekitten.com/200/200">
    <img src="http://placekitten.com/300/300">
    <img src="http://placekitten.com/400/400">
    <img src="http://placekitten.com/500/500">
</div>

CSS

div{
    float:left;
}
img{
    width:100px;
    height:100px;
}
div img{
    float:right;
}

div img:hover ~ img{
    opacity:.4;
}