Icon-search Navbar

<nav class="navbar navbar-expand-sm bg-dark navbar-dark">
  <form class="form-inline">
    <div class="input-group">
      <div class="input-group-prepend">
        <span class="input-group-text">@</span>
      </div>
      <input type="text" class="form-control" placeholder="Username">
    </div>
  </form>
</nav>
<br>