JSFiddle - React, Tailwind, and code Playground

HTML

<div id="cross"></div>

CSS

#cross {
   width: 100px;
   height: 100px;
   position: relative;
  transform:rotate(45deg);
-ms-transform:rotate(45deg); /* IE 9 */
-webkit-transform:rotate(45deg); /* Safari and Chrome */
}

#cross:before, #cross:after {
  content: "";
  position: absolute;
  z-index: -1;
  background: #d00;
}

#cross:before {
  left: 50%;
  width: 30%;
  margin-left: -15%;
  height: 100%;
}