Bootstrap 4 collapsed navbar background color

Question

I want to change background color of collapsed navbar in bootstrap 4 alpha v6. Of course I want to change the background color of whole navbar.

Answer 1

Works on v4 as well.

Here's a Bootstrap 4 alpha6 CSS walkthrough covering modifications of .navbar itself, inside links and hamburger button (all avoiding !important which should be used only as last override resort):

/* change navbar background */
nav.navbar {
  background: transparent;
}
/* change navbar-brand color */
.navbar a.navbar-brand {
  color: white;
}
/* change navbar-brand color on hover */
.navbar a.navbar-brand:hover {
  color: green;
}
/*  change navbar li colors, also active one but not disabled one */
.navbar ul.navbar-nav li.nav-item a.nav-link {
  color: white;
}
/* change navbar-toggler inside lines color (stroke) */
.navbar-light span.navbar-toggler-icon {
  background-image: url("data:image/svg+xml;charset=utf8,%3Csvg viewBox='0 0 32 32' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath stroke='yellow' stroke-width='2' stroke-linecap='round' stroke-miterlimit='10' d='M4 8h24M4 16h24M4 24h24'/%3E%3C/svg%3E");
  color: white;
}
/* change hamburger button border color */
button.navbar-toggler.navbar-toggler-right {
  border-color: yellow;
}
/* change navbar background on collapse */
@media (max-width: 768px) {
  nav.navbar {
    background: lightgray;
  }
}

<link href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/css/bootstrap.min.css" rel="stylesheet" />
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/tether/1.3.7/js/tether.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/js/bootstrap.min.js" integrity="sha384-vBWWzlZJ8ea9aCX4pEW3rVHjgjt7zpkNpZk+02D9phzyeVkE+jo0ieGizqPLForn" crossorigin="anonymous"></script>
<nav class="navbar navbar-toggleable-md navbar-light">
  <button class="navbar-toggler navbar-toggler-right" type="button" data-toggle="collapse" data-target="#navbarTogglerDemo02" aria-controls="navbarTogglerDemo02" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <a class="navbar-brand" href="#">Navbar</a>
  <div class="collapse navbar-collapse" id="navbarTogglerDemo02">
    <ul class="navbar-nav mr-auto mt-2 mt-md-0">
      <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">
        <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="text" placeholder="Search">
      <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
    </form>
  </div>
</nav>

Answer 2

This is what worked form me:

    .navbar-collapse {
    background-color: white;
}

Answer 3

"...but the case is that my background color at the beginning is transparent and then if someone will collapse it then the background color should change."

I did like this:

<style>
.navbar { 
    background-color: transparent;
}
.navbar.collapse {
    display:flex;
}
.navbar.collapsing,
.navbar.show {
    background:white !important;
}
</style>



<nav class="navbar navbar-light navbarSupportedContent">
    <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 navbarSupportedContent">
   </div>
</nav>