JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<div id="wrap">
  <div class="tr"></div>
</div>

CSS

body {
  background: #fff;
}
#wrap {
  position: relative;
  min-height: 500px;
  background: teal;
}
.tr {
  position: absolute;
  left: 0;
  top: 0;
}

JavaScript

$(document).ready(function() {
  function triangle() {
    $("#wrap .tr").css({
      "border-left": $('#wrap').width() + "px solid #fff",
      "border-bottom": "200px solid transparent"
    });
  }
  triangle();

  $(window).on('resize', triangle);
});