Ruby on Rails

<nav class="navbar navbar-expand-lg navbar-light bg-light">    <a class="navbar-brand" href="#">Navbar</a>    <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">      <span class="navbar-toggler-icon"></span>    </button>      <div class="collapse navbar-collapse" id="navbarSupportedContent">      <ul class="navbar-nav mr-auto">        <li class="nav-item active">          <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>        </li>        <li class="nav-item">          <a class="nav-link" href="#">Link</a>        </li>        <li class="nav-item dropdown">          <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">            Dropdown          </a>          <div class="dropdown-menu" aria-labelledby="navbarDropdown">            <a class="dropdown-item" href="#">Action</a>            <a class="dropdown-item" href="#">Another action</a>            <div class="dropdown-divider"></div>            <a class="dropdown-item" href="#">Something else here</a>          </div>        </li>        <li class="nav-item">          <a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>        </li>      </ul>      <form class="form-inline my-2 my-lg-0">        <input class="form-control mr-sm-2" type="search" placeholder="Search" aria-label="Search">        <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>      </form>    </div>  </nav>