JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<body>
        <form>
            <div class="form-group">
              <input type="username" class="form-control username" placeholder="Username"/>
            </div>
          <button type="submit">Sign in</button>
        </form>
</body>

CSS

@import url('http://getbootstrap.com/dist/css/bootstrap.css');