JSFiddle - React, Tailwind, and code Playground

HTML

<body>
    <header>
        <h1>Accordion</h1>
    </header>
    <main>
        <section>
            <button class="accordion">Accordion 1</button>
            <div class="panel">
            
                    <button class="accordion">Accordion xxx</button>
            <div class="panel">
                <p>aaaaaaaaaaaaaaaaaaaaa</p>

            </div>
                <p>Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet.</p>
                
  
                
                
            </div>
            <button class="accordion">Accordion 2</button>
            <div class="panel">
                <p>Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet.</p>
            </div>
            <button class="accordion">Accordion 3</button>
            <div class="panel">
                <p>Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et...

CSS

.accordion {
  background-color:lightgrey;
  color: #444;
  cursor: pointer;
  padding: 5px;
  width: 95%;
  border: none;
  outline: none;
  font-size: 20px;
  transition: 0.4s;
  margin-top:10px;
  min-width:150px;
  min-height:40px;
  border-radius:20px 20px 20px 20px;
}


.active, .accordion:hover 
{
  background-color:grey;
  color:white;
}

.accordion:after 
{
  color: #777;
  font-weight: bold;
  float: right;
  margin-left: 5px;
  margin-top:11%;
}
.active, .accordion:hover {
  background-color: grey;
  color:white;
}



.panel {
  padding: 0px ;
  background-color: white;
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.2s ease-out;
  width:100%;
  list-style: none;
  font-size:14px;
  
}

JavaScript

var acc = document.getElementsByClassName("accordion");
var i;

for (i = 0; i < acc.length; i++) {
  acc[i].addEventListener("click", function() {
    this.classList.toggle("active");
    var panel = this.nextElementSibling;
    if (panel.style.maxHeight){
      panel.style.maxHeight = null;
    } else {
      panel.style.maxHeight = panel.scrollHeight + "px";
    } 
  });
}