JSFiddle - React, Tailwind, and code Playground

HTML

<div></div>

CSS

* {
  box-sizing: inherit;
}

html {
  box-sizing: border-box;
}
body {
  margin: 0;
  padding: 20px;
}

div {
  width: 1000px;
  height: 200px;
  
  background:  linear-gradient(3deg, transparent 15px, red 17px, red calc(100% - 17px), transparent calc(100% - 15px)) no-repeat left / 33.33% 100%, linear-gradient(-3deg, transparent 15px, red 17px, red calc(100% - 17px), transparent calc(100% - 15px)) no-repeat center / 33.4% 100%, linear-gradient(3deg, transparent 15px, red 17px, red calc(100% - 17px), transparent calc(100% - 15px)) no-repeat right / 33.33% 100%;
  background-color: #999;
}