cabecalho.php

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <!-- Container wrapper -->
  <div class="container-fluid">
    <!-- Toggle button -->
    <button class="navbar-toggler" type="button" data-mdb-toggle="collapse" data-mdb-target="#navbarCenteredExample" aria-controls="navbarCenteredExample" aria-expanded="false" aria-label="Toggle navigation" >
      <i class="fas fa-bars"></i>
    </button>

    <!-- Collapsible wrapper -->
    <div class="collapse navbar-collapse justify-content-center" id="navbarCenteredExample" >
      <!-- Left links -->
      <ul class="navbar-nav mb-2 mb-lg-0">
            <li class="nav-item">
                <a class="nav-link" href="qr-manual.php">Manual</a>
            </li>
            <li class="nav-item">
                <a class="nav-link" href="qr-auto.php">Automático</a>
            </li>
        <div class="dropdown">
        <a class="nav-link dropdown-toggle" href="#" role="button" data-bs-toggle="dropdown" aria-expanded="false"> Registros </a>
            <ul class="dropdown-menu">
                <li><a class="dropdown-item" href="consultar-registros.php">Consultar</a></li>
                <li><a class="dropdown-item" href="apagar-registros.php">Apagar</a></li>
            </ul>
        </div>
      </ul>
    </div>
  </div>
</nav>