Bootstrap Corporate website

Expected behavior when i click dropdown menu it should open the list .and after resizing the window navbar should work Actual behavior but it s not opening the list when i click the dropdown menu..and after resizing the window/chrome the navbar is also not working Resources (screenshots, code snippets etc.)

H1 Tech

  <!-- Links -->
  <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="#">Features</a>
      </li>
      <li class="nav-item">
          <a class="nav-link" href="#">Pricing</a>
      </li>

      <!-- Dropdown -->
      <li class="nav-item dropdown">
          <a class="nav-link dropdown-toggle" id="navbarDropdownMenuLink" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">Dropdown</a>
          <div class="dropdown-menu dropdown-primary" aria-labelledby="navbarDropdownMenuLink">
              <a class="dropdown-item" href="#">Action</a>
              <a class="dropdown-item" href="#">Another action</a>
              <a class="dropdown-item" href="#">Something else here</a>
          </div>
      </li>

  </ul>
  <!-- Links -->

  <form class="form-inline">
      <div class="md-form my-0">
          <input class="form-control mr-sm-2" type="text" placeholder="Search" aria-label="Search">
      </div>
  </form>