Double navbar (1st hiding and 2nd stickying at the top)

dblnavbar.html

<nav class="navbar-custom-top">
        <div class="container">
            <a class="navbar-brand heading" href="index.html#pagetop">Humboldt</a>
            <div class="float-right topnav-right-button">
                <a class="bg-heading p-3" href="">Sign up</a>
            </div>
        </div>
      </nav>

      <nav class="navbar navbar-expand-lg navbar-light navbar-custom sticky-top" id="navbartag">
        <button aria-controls="navbarResponsive" aria-expanded="false" aria-label="Toggle navigation"
                class="navbar-toggler text-dark" data-target="#navbarResponsive" data-toggle="collapse" type="button">
          <span class="navbar-toggler-icon"></span>
        </button>
        <div class="collapse navbar-collapse" id="navbarResponsive">
          <ul class="navbar-nav mx-auto">
            <li class="nav-item">
              <a class="nav-link js-scroll-trigger text-secondary" href="index.html#about">About Us</a>
            </li>
            <li class="nav-item">
              <a class="nav-link js-scroll-trigger text-secondary" href="index.html#propriedades">Support Us</a>
            </li>
            <li class="nav-item">
              <a class="nav-link js-scroll-trigger text-secondary" href="index.html#projetos">Preview</a>
            </li>
          </ul>
        </div>
      </nav>