My problem arises when putting the small version (mobile) with the menu, you know that with bootstrap when you increase the size of a menu it becomes a button with a drop-down with the icon of three dashes, well then my problem that little button when I give it to unfold I throw down the content that is directly below the menu, and what I want is to overlap the content that is below, because as I have it mounted right now what it does is push all the content below the menu down
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Maquetado v.1</title>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js" integrity="sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js" integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl" crossorigin="anonymous"></script>
</head>
<style>
.efecto_boton{
border: 1px solid orange; /* Color del borde, debe ser más oscuro que fondo */
background: orange; /* Fondo */
border-radius: 6px; /* Bordes redondos */
box-shadow: inset 3px 3px 3px rgba(255,255,255,.7), inset -2px -2px 3px rgba(0,0,0,.1), 2px 2px 10px rgba(0,0,0,.1);
text-shadow: 1px 1px 1px rgba(255,255,255,.9); /* Sombra del texto */
/*text-align: center; Alineación del texto */
}
.menu{
border: 1px solid green; /* Color del borde, debe ser más oscuro que fondo */
background: green; /* Fondo */
border-radius: 6px; /* Bordes redondos */
box-shadow: inset 3px 3px 3px rgba(255,255,255,.7), inset -2px -2px 3px rgba(0,0,0,.1), 2px 2px 10px rgba(0,0,0,.1);
text-shadow: 1px 1px 1px rgba(255,255,255,.9); /* Sombra del texto */
/*text-align: center; Alineación del texto */
margin-top: 20px;
margin-bottom: 20px;
z-index: 0;
}
.imagen_prueba{
background-image: url('https://www.tuexperto.com/wp-content/uploads/2017/10/fondo-de-pantalla-paisaje-768x432.jpg');
background-repeat: no-repeat;
background-size: cover;
width: 200px;
height: 200px;
}
</style>
<body>
<div class="container-fluid">
<div class="row">
<!-- tiitutlo -->
<div class="col-lg-12 col-md-12 col-sm-12 col-xs-12 efecto_boton">
<h1 class="text-primary text-center " >Maquetado v.1</h1>
</div>
</div>
<div>
<!-- menu -->
<nav class="navbar navbar-expand-lg navbar-light bg-light menu">
<a class="navbar-brand" href="#">Menu</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">
<li class="nav-item active">
<a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Link</a>
</li>
<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">
Dropdown
</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdown">
<a class="dropdown-item" href="#">Action</a>
<a class="dropdown-item" href="#">Another action</a>
<div class="dropdown-divider"></div>
<a class="dropdown-item" href="#">Something else here</a>
</div>
</li>
<li class="nav-item">
<a class="nav-link disabled" href="#">Disabled</a>
</li>
</ul>
<form class="form-inline my-2 my-lg-0">
<input class="form-control mr-sm-2" type="search" placeholder="Search" aria-label="Search">
<button class="btn btn-primary my-2 my-sm-0" type="submit">Search</button>
</form>
</div>
</nav>
<!-- fin menu -->
</div>
</div>
<div class="row">
<div class="col-3 text-left">
<!-- col izq -->
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<imgS src="" alt="">
</div>
<div class="col-6 text-center">
<!-- col cent -->
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<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Illo in nesciunt quas architecto minus inventore debitis modi harum vero veritatis unde molestias, cum tenetur doloremque et est quae laudantium soluta.</p>
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<div class="container-fluid imagen_prueba">
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<br>
<br>
<br>
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</div>
</div>
<div class="col-3 text-right">
<!-- col der -->
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</div>
</div>
</div>
</body>
</html>
So if someone knows how to superimpose the menu on the body of the page I would be very grateful, I have tried many things and I have not achieved it. I've also found something of a CSS property called z-index or something like that, but it's not being used correctly for what I see. Thank you very much in advance
