JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
    <li>Item 1</li>
    <li>Item 2</li>
    <li>Item 3</li>
    <li>Item 4</li>
    <li>Item 5</li>
</ul>

CSS

ul:hover li {
    opacity: 0.5;
}

ul:hover li:hover {
   opacity: 1 ;
}