JSFiddle - React, Tailwind, and code Playground

HTML

<!doctype html>
<html>
<head>
</head>
<body>

    <div class="box"></div>
</body>
</html>

CSS

.box {
    position: absolute;
    top: 50%;
    left: 50%;
    width: 400px;
    height: 200px;
    margin-top: -100px;
    margin-left: -200px;
    background: #00A4DD;
    border-top: solid #7ccbea 7px;
    border-left: solid #7ccbea 7px;
    -webkit-transition: all ease 0.3s;
}

.box:before {
  content: '';
  position: absolute;
  left: -15px;
  bottom: -15px;
  border: solid transparent 15px;
  border-left-color: #fff;
}

.box:after {
  content: '';
  position: absolute;
  top: -30px;
  right: 0;
  border: solid transparent 15px;
  border-right-color: #fff;
}

.box:hover {
  border-width: 15px;
}