JSFiddle - React, Tailwind, and code Playground

HTML

<div id="content">
    <h1>Corner Peel Demo</h1>
</div>
<div id="content-bottom">
    <div id="content-space"></div>
    <div id="content-corner"></div>
</div>

CSS

body{
    background: red;
}
div#content{
  min-height: 250px;
  min-width: 250px;
  background-color: #fff;
  border-radius: 9px;
  border-bottom-right-radius: 0px;
  border-bottom-left-radius: 0px;
  margin: 5px 5px 0;
}
div#content-bottom {
  height: 30px;
  margin: 0 5px;
  position: relative;
}
div#content-space {
  height: 27px;
  border-bottom-left-radius: 9px;
  background-color: #fff;
  margin-right: 42px;
}

div#content-corner {
  position: absolute;
  top: 0px;
  right: 0px;
  height: 27px;
  width: 42px;
  background-color: transparent;
  background-image: url(data:image/png;base64,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%3D);
}