JSFiddle - React, Tailwind, and code Playground

HTML

<div class="search-field">
</div>
<form role="search" method="get" class="search-form" action="<?php echo home_url( '/' ); ?>">
  <label for="search-input" id="search-label" class="search-label">
    Search for:   
    </label>
<input id="search-input" type="search" class="search-input" placeholder="Search …" value="" name="s" title="Search for:" />
  <input type="submit" class="search-submit" value="Search" />
</form>

CSS

#ht-masthead .search-field {
  background-color: transparent;
  background-image: url(images/search-icon.png);
  background-position: 5px center;
  background-repeat: no-repeat;
  background-size: 24px 24px;
  border: none;
  cursor: pointer;
  height: 37px;
  margin: 3px 0;
  padding: 0 0 0 34px;
  position: relative;
  -webkit-transition: width 400ms ease, background 400ms ease;
  transition: width 400ms ease, background 400ms ease;
  width: 230px;
}

#ht-masthead .search-field:focus {
  background-color: #fff;
  border: 2px solid #c3c0ab;
  cursor: text;
  outline: 0;
}
#ht-masthead .search-form {
  display: none;
  position: absolute;
  right: 200px;
  top: 200px;
}
.search-toggle:hover #ht-masthead .search-form {
  display: block;
}
.search-form
    .search-submit {
  display: none;
}

.search-form {
  position: relative;
}

.search-form label {
  position: relative;
  background: url('https://cdn4.iconfinder.com/data/icons/ionicons/512/icon-ios7-search-strong-128.png') 0 0 no-repeat;
  background-size: cover;
  width: 50px; height: 50px;
  text-indent: 9999px;
  overflow: hidden;
  white-space: nowrap;
}

.search-input {
  transform: translateY(-100%);
  opacity: 0;
  position: absolute;
  top: 100%;
  transition: opacity .25s, transform .25s;
  left: 0;
  z-index: -1;
  border: 0;
  outline: 0;
  
}
.search-label, .search-input {
  background: #ccc;
  padding: .5em;
  display: inline-block;
}

.clicked + .search-input {
  opacity: 1;
  transform: translateY(0);
}

JavaScript

document.getElementById("search-label").addEventListener("click", function(e) {
  if (e.target == this) {
    e.preventDefault();
    this.classList.toggle("clicked");
  }
});