JSFiddle - React, Tailwind, and code Playground

HTML

<!-- HTML -->
<div id='passf'>
 <a id="opener" href="#">Login</a>
  <div id="open">
    <label>Name
      <input placeholder='Name' type='text' name='name' value=''>
    </label>
    <label>Passwort
      <input placeholder='Passwort' type='password' name='pass' value=''>
    </label>
  </div>
</div>
<!-- HTML ends -->

SCSS

input {
  width:100%
}
#passf {
  padding:10px;
  border:1px solid blue;
}

.js_active #open {
  display:none;
  padding:10px;
  border:1px solid red;
}

JavaScript

document.documentElement.className = "js_active";

$('#opener').on('click', function() {
  $("#open").toggle(250);
});