JSFiddle - React, Tailwind, and code Playground

HTML

<div id="content">
   hello
</div>

CSS

@-webkit-keyframes pulseBorder {
  from {
    border:solid 1px #f00;
  }
  to {
    border:solid 10px #f00;
        
  }
}

div {
  -webkit-animation-name: pulseBorder;
  -webkit-animation-iteration-count: infinite;
  -webkit-animation-timing-function: ease;
  -webkit-animation-direction: alternate;
  -webkit-animation-duration: 0.5s;
    text-align:center;
    border: solid 1px #f00
}