Bootstrap navbar-Single item doesn't show up when on mobile-CodePudding

I'm building a small portfolio site and I'm using bootstrap for the navigation bar, I modified a bit with things such as a different background and fonts. I'm not sure what is missing exactly, but the last item, called "language", which is a dropdown, simply doesn't seem to show up when I change the window size.

I made a codepen with the relevant code in it, sorry for any obvious mistake as I've just started out using it seriously:

https://codepen.io/bladeranner5005/pen/ExwpMpq

HTML:

<!doctype html>
<html lang="it">
<head>
    <!--Required meta tags-->
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">

    <!--Font links-->
    <link rel="preconnect" href="https://fonts.googleapis.com">
    <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
    <link href="https://fonts.googleapis.com/css2?family=Josefin Sans:wght@300;400&family=Libre Franklin:wght@800&display=swap" rel="stylesheet">

    <!--Bootstrap CSS-->
    <link href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-1BmE4kWBq78iYhFldvKuhfTAU6auU8tT94WrHftjDbrCEXSU1oBoqyl2QvZ6jIW3" crossorigin="anonymous">

    <!--My Css-->

    <!--Icons links-->

    <!--Custom css-->
    <link href="Index-css.css" rel="stylesheet">


    <title>Andrea D'Angelo-portfolio</title>
</head>

<body>

<!-- NAVBAR ----------------------------------------------------------------------------------------------------------->
<!--Modified bootstrap NAVBAR, with different colors and positioning when in desktop----------------------------------->

<nav >



    <a  href="#"></a>
    <button  type="button" data-toggle="collapse" data-target="#navbarNavAltMarkup" aria-controls="navbarNavAltMarkup" aria-expanded="false" aria-label="Toggle navigation">
        <span ></span>
    </button>
    <div  id="navbarNavAltMarkup">
        <div >
            <a  href="#">Home</a>
            <a  href="#">Curriculum</a>
            <a  href="#">Portfolio</a>
            <a  href="#">Contatti</a>

            <!--Codice per il dropdown da: https://stackoverflow.com/questions/17904862/bootstrap-position-of-dropdown-menu-relative-to-navbar-item-->
            <div  id="navbarSupportedContent">
                <ul >
                    <li >
                        <a  href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                            Language
                        </a>
                        <div  aria-labelledby="navbarDropdown">
                            <a  href="#">
                                <span></span>
                                Ita</a>
                            <a  href="#">
                                <span></span>
                                Eng</a>
                        </div>
                    </li>
        </div>

            <!--Dropdown item end-->

    </div>
    </div>
</nav>

<!--Main tag----------------------------------------------------------------------------------------------------------->

<main>

<!--HOME-Logo animation------------------------------------------------------------------------------------------------>



</main>

<!-- Javascript for Bootstrap --------------------->
<!-- Optional JavaScript; choose one of the two! -->

<!-- Option 1: Bootstrap Bundle with Popper -->
<script src="https://code.jquery.com/jquery-3.4.1.slim.min.js" integrity="sha384-J6qa4849blE2 poT4WnyKhv5vZF5SrPo0iEjwBvKU7imGFAV0wwj1yYfoRSJoZ n" crossorigin="anonymous"></script>
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/umd/popper.min.js" integrity="sha384-Q6E9RHvbIyZFJoft 2mJbHaEWldlvI9IOYy5n3zV9zzTtmI3UksdQRVvoxMfooAo" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/js/bootstrap.min.js" integrity="sha384-wfSDF2E50Y2D1uUdj0O3uMBJnjuUD4Ih7YwaYd1iqfktj0Uod8GCExl3Og8ifwB6" crossorigin="anonymous"></script>
<!-- Javascript for Bootstrap END------------------>

</body>
</html>

CSS:

/*ESSENTIAL ----------------------------------------------------------------------------------------------------------*/
body {
    padding-top: 70px;
} /*Per non far coprire contenuti dal navbar, source: https://stackoverflow.com/questions/11124777/twitter-bootstrap-navbar-fixed-top-overlapping-site --*/

html {
    scroll-behavior: smooth;
}

/*FONTS --------------------------------------------------------------------------------------------------------------*/

/*Tags from google fonts

Josefin sans light:

font-family: 'Josefin Sans', sans-serif;
font-weight: 300;

Josefin sans regular:

font-family: 'Josefin Sans', sans-serif;
font-weight: 400;

Libre Franklin
font-family: 'Libre Franklin', sans-serif;
font-weight: 800;
*/



/*NAVBAR -------------------------------------------------------------------------------------------------------------*/

/*Structure --*/

.nav-item-spacing {
    margin-left:30px;
    margin-right:30px;
}

/*Colors --*/

.navbar-black {
    background: black;
}

.nav-link-custom-1 {
    font-family: 'Libre Franklin', sans-serif;
    font-weight: 800;
}

.nav-link-custom-2 {
    font-family: 'Josefin Sans', sans-serif;
    font-weight: 400;
}

CodePudding user response：

Remove:

<div  id="navbarSupportedContent">
            <ul >

from before the "language" dropdown in your html (also remove the </div> ) There doesn't seem to be a purpose of having that again.