JSFiddle - React, Tailwind, and code Playground

HTML

<body>
    <div id="one">
       
    </div>
    <div id="two">
            
    </div>
</body>

CSS

#one {
            width: 500px;
            background-color: aqua;
            height: 300px;
        }
        #two{
            border-top: 100px solid red;
            border-right: 250px solid transparent;
            border-bottom: 100px solid transparent;
            border-left: 250px solid transparent;
            width: 0;
            height: 0;
            
        }