Olha ai o meu html
<!doctype html>
<head>
<meta charset="utf-8">
<!-- CSS -->
<link href="public/css/bootstrap.min.css" rel="stylesheet">
</head>
<body>
<nav class="navbar fixed-top bg-danger navbar-dark">
<button class="btn dropdown-toggler" type="button" data-toggle="dropdown" data-target="#menu">
<span class="navbar-toggler-icon"></span>
</button>
<a href="#" class="navbar-brand">LOGO</a>
<!-- links -->
<div id="menu" class="dropdown-menu">
<a class="dropdown-item" href="#">Home</a>
<a class="dropdown-item" href="#">Quem somos</a>
<a class="dropdown-item" href="#">Serviços</a>
<a class="dropdown-itm" href="#" id="menu_dropdown" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">Sites</a>
<div class="dropdown-menu2">
<a href="<a href="http://meumundo.com" target="_blank">http://meumundo.com</a>" class="dropdown-item">meumundo</a>
<a href="<a href="http://M!dium.com.br" target="_blank">http://M!dium.com.br</a>" class="dropdown-item">M!dium</a>
</div>
<a class="nav-link" href="#">Fale conosco</a>
<form class="form-inline">
<div class="input-group">
<input type="text" placeholder="Buscar" name="buscar" class="form-control input-group-prepend">
<input type="submit" class="btn btn-success input-group-append">
</div>
</form>
</div>
</nav>
<footer>
<!-- JS -->
</footer>
</body>
</html>Valeu
Navegar é preciso, viver... também. 
