i'm on my first bootstrap site and I have a problem. My Navigation is always collapsed, even in screen size. The hamburger icon works, but it should only be there in mobile-screen-sizes.
Can everyone help me?
<div class="header-nav clearfix">
<nav class="navbar navbar-fixed-top">
<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="navbar-collapse collapse " id="navbarSupportedContent">
<ul class="nav">
<li class="nav-item">
<a class="nav-link" href="#">Über uns</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Karriere</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Downloads</a>
</li>
<li class="nav-item nav-item-gruen">
<a class="nav-link" href="#">Kontaktieren Sie uns!</a>
</li>
</ul>
</div>
</nav>
</div>