<nav class="navbar navbar-expand-md navbar-dark fixed-top bg-dark">
  <a class="navbar-brand" href="cliente.php"><img src="../Foto_exportadora/<?php echo $cliente; ?>.jpeg" width="40"></a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarCollapse" aria-controls="navbarCollapse" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <div class="collapse navbar-collapse" id="navbarCollapse">
    <ul class="navbar-nav mr-auto">
      <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">
          Informes
        </a>
        <div class="dropdown-menu" aria-labelledby="navbarDropdown">
          <?php 
          $vista = "";
          if(isset($_REQUEST['cliente'])){
            $vista = $_REQUEST['cliente'];
          }
          ?>
          <a class="dropdown-item <?php if($vista == "graficos") echo "active"; ?>" href="cliente.php?cliente=graficos">Gráficos</a>
        </div>
      </li>
    </ul>
    <a class="nav-link" href="../cierra_sesion.php">Cerrar Sesión</a>
  </div>
</nav>