Cabeçalho

<div style="background-image:url(banner.jpg); background-size:cover; background-repeat:no-repeat; width:100%; height:250px; text-align:right">
    <!--Navbar-->
    <div id="nav">
    <nav class="navbar navbar-expand-lg navbar navbar-light" style="background-color: #e3f2fd;">
        <a class="navbar-brand" href="index.php">
            <img src="R.png" width="30" height="30" class="d-inline-block align-top" alt="R">
        </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">
            <?php
                $ms = new mysqli($bd_host,$bd_user,$bd_password,$bd_database);
                $ms->set_charset("utf8");
                if ($ms->connect_error){
                        die();
                    }
                if(!empty($_SESSION["nid"]) && !empty($_SESSION['num'])){
                    $tp=$_SESSION['tipo'];
                }
                else{
                    $tp=0;
                }
                $sql = "SELECT * FROM menu WHERE permissao<=" . $tp;
                $listart = $ms->query($sql);
                while($row1 = $listart->fetch_array()){
                ?>
                    <li class="nav-item active">
                        <a class="nav-link" onclick="window.open('<?php  echo $row1["link"]; ?>', '_self');" style=" cursor: pointer;" id="<?php  echo $row1['idmenu']; ?>" ><?php  echo $row1["nome"];?></a>
                    </li>
                    &nbsp;&nbsp;
                <?php } ?>
            </ul>
                <?php
                if(empty($_SESSION["nid"]) || $_SESSION["nid"]!=session_id()){ ?>
                    <form class="form-inline my-2 my-lg-0" method="post"action="index.php">
                        <input class="form-control mr-sm-2" type="email" placeholder="E-mail" aria-label="Search" name="email">
                        <input class="form-control mr-sm-2" type="text" placeholder="Password" aria-label="Search" name="pass">
                        <button class="btn btn-outline-success my-2 my-sm-0" type="submit" name="login">Login</button>&nbsp;&nbsp;
                        <button class="btn btn-outline-primary" type="submit" onclick="window.open('registar.php');">Registar</button>
                    </form>
                <?php
                }
                include 'valida.php';
                if(!empty($_SESSION["nid"]) && !empty($_SESSION['num'])){
                    ?>
                        <form class="form-inline my-2 my-lg-0" method="post"action="index.php">
                            <label>Bem vindo, <?php echo $_SESSION["nome"]; ?>&nbsp;&nbsp;</label>
                            <button class="btn btn-outline-danger my-2 my-sm-0" type="submit" name="logout">Logout</button>
                        </form>
                    <?php
                }?>
        </div>
    </nav>
    </div>
</div>