JSFiddle - React, Tailwind, and code Playground

HTML

<form id="formElement">
    One: <input type="text"><br>
    Two: <input type="text">
</form>

CSS

.focused {
    outline: solid 2px red;
}

JavaScript

Array.prototype.forEach.call(document.querySelectorAll('#formElement input'), function(input) {

  input.onfocus = function(){
  	this.classList.add('focused');
  }
  
  input.onblur = function(){
  	this.classList.remove('focused');
  }
  
})