JSFiddle - React, Tailwind, and code Playground

HTML

<div id="trapezoid"></div>

CSS

#trapezoid {
    border-bottom: 100px solid steelblue;
    border-left: 50px solid transparent;
    border-right: 50px solid transparent;
    height: 0;
    width: 200px;
    transform: rotate(180deg);
}