JSFiddle - React, Tailwind, and code Playground

HTML

<div id="wrapper">
        <ul class="nav">
            <li>first line</li>
            <li>second line，将会被下面的 jQuery 语句选中并改变背景颜色</li>
            <li>third line</li>   
            <li>four line</li>      
        </ul>
    </div>

CSS

#wrapper li{
    
color:white;
    
background:#333;
    
}

JavaScript

$("#wrapper li:first-child").next().css("background", "#0175cc");