JSFiddle - React, Tailwind, and code Playground

HTML

<div id="wrapper">
    <div class="container">
        <div class="nav">
            <p>tessssssssssssssst</p>
         <div>
    </div>
</div>

CSS

#wrapper .container .nav{  
            background-color: red;
            opacity: 0.3;        
}

#wrapper .nav {
    opacity: 1.0;
}