JSFiddle - React, Tailwind, and code Playground

by Paqura

HTML

<section class="block-about">
	<div class="block-about__wrapper">
     <div class="element__wrapper">
		<button class="block-about__btn  about-btn__active"></button>
		<div class="block-about__content  about-active">
			<h3 class="block-about__content_header">What Out Client Say</h3>
			<p class="block-about__content_descr">Lorem ipsum dolor sit amet, consectetur adipisicing elit. Vel tempora vero, atque id omnis expedita.</p>
			<hr>
			<span class="block-about__content_name">Kevin Samsung</span>
			<span class="block-about__content_works">CEO/Task</span>
		</div>
	</div>

 <div class="element__wrapper">
		<button class="block-about__btn"></button>
		<div class="block-about__content">
			<h3 class="block-about__content_header">Said For Us</h3>
			<p class="block-about__content_descr">Lorem ipsum dolor sit amet, consectetur adipisicing elit. Explicabo quod impedit, ab, vero reiciendis, iusto quis, culpa quidem sunt quas minus dignissimos ducimus sint nemo!.</p>
			<hr>
			<span class="block-about__content_name">Kevin Samsung</span>
			<span class="block-about__content_works">CEO/Task</span>
		</div>
 </div>
 <div class="element__wrapper">
	   <button class="block-about__btn"></button>
	   <div class="block-about__content">
		   <h3 class="block-about__content_header">What Out Client Say</h3>
		   <p class="block-about__content_descr">Lorem ipsum dolor sit amet, consectetur adipisicing elit. Vel tempora vero, atque id omnis expedita.</p>
		   <hr>
		   <span class="block-about__content_name">Kevin Samsung</span>
		   <span class="block-about__content_works">CEO/Task</span>
	   </div>
 </div>
 <div class="element__wrapper">
	  <button class="block-about__btn"></button>
	  <div class="block-about__content">
		  <h3 class="block-about__content_header">What Out Client Say</h3>
		  <p class="block-about__content_descr">Lorem ipsum dolor sit amet, consectetur adipisicing elit. Vel tempora vero, atque id omnis expedita.</p>
		  <hr>
		  <span...

CSS

@import "bourbon";
@import "../../prework/vars";
@import "../../prework/base";

.block-about {
  height: 100%;
  width: 100%;
  background-color: #3b3342;
  position: relative;
}

.block-about__wrapper {
	width: 60%;
	margin: 0 auto;
	position: relative;
	padding-top: 7%;
}


.block-about__btn {
	max-width: 20%;
	width: 8%;
	max-height: 80%;
	height: 10%;
	background-color: #fff;
	border: none;
	cursor: pointer;
	padding-bottom: 10%;
	opacity: .2;
	transition: opacity .5s ease;
}

.block-about__btn:hover {
	opacity: 1;
}

.block-about__content {
	display: none;
}

@keyframes mymove {
    0%   {top: -1000px;}
    100% {	top: 45%;}
}

.about-active {
	display: block;
	position: absolute;
	top: 25%;
	right: 0;
	width: 70%;
	float: right;
	animation: mymove .5s ease-in-out;
}

.about-btn__active {
	opacity: 1;
	background-image: url('../img/about_one.png');
	background-repeat: no-repeat;
	max-width: 20%;
	width: 8%;
	max-height: 30%;
	height: 10%;
	background-color: transparent;
	border: none;
	cursor: pointer;
	padding-bottom: 10%;
}

Babel + JSX

"use strict";

const items = document.getElementsByClassName('block-about__btn');

for (let i = 0; i < items.length; i++) {
	let key = items[i];
	key.addEventListener('click', function(e) {
		e.preventDefault();
		let classContentLength = this.nextElementSibling.classList.length;
		let classBtnLength = this.classList.length;

		if (classBtnLength <= 1 || classContentLength <= 1) {
			this.classList.add("about-btn__active");
			this.nextElementSibling.classList.add('about-active');
		} else {
			this.classList.remove("about-btn__active");
			this.nextElementSibling.classList.remove('about-active');
		}
	});
};