JSFiddle - React, Tailwind, and code Playground

HTML

<p>Логин</p> <input type="text">
<p>Пароль</p> <input type="text">

CSS

.highlight { background: #FA6; }

JavaScript

inputs = document.getElementsByTagName('input');

for (input in inputs) {
	if (parseInt(input).toString() == 'NaN') continue;
	inputs[input].onfocus = function() {this.className = 'highlight';};
	inputs[input].onblur = function() {this.className = '';};
	}