JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html>
<head>
</head>
<body>

<div id="arrow"></div>

</body>
</html>

CSS

#arrow {
  position: relative;
  width: 0;
  height: 0;
  border-top: 9px solid transparent;
  border-right: 9px solid transparent;
  -webkit-transform: rotate(10deg);
  -moz-transform: rotate(10deg);
  -ms-transform: rotate(10deg);
  -o-transform: rotate(10deg);
}
#arrow:after {
  content: "";
  position: absolute;
  border: 0 solid transparent;
  border-top: 3px solid red;
  border-radius: 20px 20px 0 0;
  top: -12px;
  left: -9px;
  width: 12px;
  height: 12px;
  -webkit-transform: rotate(45deg);
  -moz-transform: rotate(45deg);
  -ms-transform: rotate(45deg);
  -o-transform: rotate(45deg);
}