JSFiddle - React, Tailwind, and code Playground

HTML

<div class="explore" id="explore">
  <div class="explore_body">
    <h4 style="text-align: center; margin-bottom: -10px; ">explore by theme:</h4>
    <ul id="nav">
      <li onclick="selectMe(this)"><a href="#!"><img src="images/air_pollution.png" /></a><a href="#!" class="album_title">Air pollution and air quality</a></li>
      <li onclick="selectMe(this)"><a href="#!"><img src="images/biodiversity.png"/></a><a href="#!" class="album_title">Biodiversity</a></li>
      <li onclick="selectMe(this)"><a href="#!"><img src="images/chemicals_and_wastes.png"/></a><a href="#!" class="album_title">Chemicals and waste</a></li>
    </ul>
  </div>
</div>

CSS

.explore {
  margin-left: auto;
  margin-right: auto;
  width: 1020px;
  margin-top: 20px;
}

.explore_body {
  width: 100%;
  /* border: 1px solid #f00; */
  padding-bottom: 5px;
  padding-top: 5px;
  clear: both;
  background: #f0f0f0;
  *background: #f0f0f0;
  /* star hack to target IE6 & 7*/
}

.explore_body ul {
  margin: 5px;
  padding-top: 5px;
  clear: both;
  width: 100%;
}

.explore_body ul li {
  display: inline-block;
  /*IE7 doesn't support inline-block */
  zoom: 1;
  *display: inline;
  /* star hack to target IE6 & 7*/
  /* background: url(images/album.png); */
  width: 130px;
  height: 145px;
  margin: 5px 5px;
}

.explore_body ul li img {
  width: 120px;
  height: 100px;
  margin: 5px 0px 5px 5px;
}

.explore_body ul li {
  opacity: 0.9;
  filter: alpha(opacity=90);
  /* For IE8 and earlier */
}

.explore_body ul li:hover {
  opacity: 1;
  filter: alpha(opacity=100);
  /* For IE8 and earlier */
  -webkit-box-shadow: 3px 3px 3px 3px #666;
}

.explore_body ul li:selected {
  opacity: 1;
  filter: alpha(opacity=100);
  /* For IE8 and earlier */
  -webkit-box-shadow: 3px 3px 3px 3px #666;
}

.active {
  opacity: 1;
  filter: alpha(opacity=100);
  /* For IE8 and earlier */
  -webkit-box-shadow: 3px 3px 3px 3px #666;
}

.active2 {
  background-color: #cedff8;
}

JavaScript

function selectMe(el) {
  var lis = document.getElementById("nav").getElementsByTagName("li");
  for (i = 0; i < lis.length; i++) {
    lis[i].classList.remove('active')
  }
  el.classList.add('active');
}