JSFiddle - React, Tailwind, and code Playground

HTML

<div class="wrapper">
    <div class="triangle"></div>
</div>

CSS

.wrapper{
    width:300px;
    background-color:orange;
}
.triangle {
   width:0;
   border-width: 30px;
   border-right:0px;
   border-color: transparent transparent transparent yellow;
   border-style: solid;   
}