JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://code.jquery.com/jquery-3.4.1.slim.js"></script>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.css">
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.16.0/umd/popper.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/js/bootstrap.js"></script>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.css">
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/animate.css/4.1.0/animate.min.css">
<div>
  <div class="row button-container">
    <div class="col" style="display: flex;">
      <div id="sideExpand"><select>
          <optgroup label="This is a group">
            <option value="12" selected>This is item 1</option>
            <option value="13">This is item 2</option>
            <option value="14">This is item 3</option>
          </optgroup>
        </select><select>
          <optgroup label="This is a group">
            <option value="12" selected>This is item 1</option>
            <option value="13">This is item 2</option>
            <option value="14">This is item 3</option>
          </optgroup>
        </select><select>
          <optgroup label="This is a group">
            <option value="12" selected>This is item 1</option>
            <option value="13">This is item 2</option>
            <option value="14">This is item 3</option>
          </optgroup>
        </select></div>
      <button class="btn btn btn-transparent btn-icon" id="filterToggle" onclick="SetActiveDiv('#sideExpand',this)"><i class="fa fa-filter" style="position: absolute;font-size: 150%;"></i></button>
    </div>
  </div>
</div>

CSS

#sideExpand {
  display: none;
  width: 100%;
  border-radius: 35px;
  background-color: rgba(31, 45, 65, 0.125);
}
select {
  border: 0;
  background-color: initial;
  font-size: 100%;
  display: block;
  margin: auto;
  word-wrap: normal;
}


.btn-icon {
  padding: 0;
  display: -webkit-inline-box;
  display: inline-flex;
  -webkit-box-align: center;
  align-items: center;
  -webkit-box-pack: center;
  justify-content: center;
  overflow: hidden;
  border-radius: 100%;
  flex-shrink: 0;
  height: calc( (1rem * 1.5) + (0.5rem * 2) + (2px) ) !important;
  width: calc( (1rem * 1.5) + (0.5rem * 2) + (2px) ) !important;
}

JavaScript

function SetActiveDiv(ID, bt) {
  var element = document.querySelector(ID);
  if (element !== null) {
  
    if (element.classList.contains("show")) {
      element.classList.remove("show");
      animateCSS(element, "fadeOutLeftBig", "2s")
      animateCSS(bt, "fadeOutLeftBig", "2s")
      return setTimeout(() => {
        element.style.display = "none";
      }, 2000);
    } else {
      element.style.display = "flex";
      element.classList.add("show");
      animateCSS(element, "fadeInLeftBig", "2s").then((message) => {});
      return animateCSS(bt, "fadeInLeftBig", "2s").then((message) => {});
    }
  }
  return console.log(ID, " not found!");
}