This question has already asked, but my issue is a little different.
Bootstrap menu (nav) collapse horizontally instead of vertical
Change bootstrap navbar collapse breakpoint without using LESS
When I resize, the navbar collapses. But when I click the button icon, I still have an horizontal menu. 
Here are the pictures:

here is my code.
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
</head>
<body>
<div>
<div>
    <div class="jumbotron" style="padding: 0px">
        <div class="card fancy-card">
<div class="card">
    <div class="container">
        <nav class="navbar navbar-default" style="background-color: lightskyblue">
            <div class="container-fluid">
                <div class="navbar-header">
                    <button type="button" class="navbar-toggle collapsed" data-toggle="collapse"
                    data-target="#bs-example-navbar-collapse-1" aria-expanded="false">
                    <span class="sr-only">Toggle navigation</span>
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                </button>
                <a class="navbar-brand sr-only" href="#">Menu</a>
            </div>
            <!--class="collapse navbar-collapse" to hide some elts of menu-->
            <div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
                <ul class="nav navbar-nav">
                                    <li>
                                        <a routerLink="/home/accueil" routerLinkActive="active">home</a>
                                    </li>
                                    <li>
                                        <a href="javascript:void(0)"
                                        class="dropdown-toggle"
                                        data-toggle="dropdown">Item1<span class="caret"></span></a>
                                        <ul class="dropdown-menu">
                                            <li><a routerLink="/home/item11" routerLinkActive="active">Item11</a>
                                            </li>
                                            <li><a routerLink="/home/item12"
                                             routerLinkActive="active">Item12</a></li>
                                        </ul>
                                    </li>
                                    <li>
                                        <a  href="javascript:void(0)"
                                        class="dropdown-toggle"
                                        data-toggle="dropdown">Item2<span class="caret"></span></a>
                                        <ul class="dropdown-menu">
                                            <li><a routerLink="/home/item21" routerLinkActive="active">Item21</a>
                                            </li>
                                            <li><a routerLink="/home/item21" routerLinkActive="active">Item22</a>
                                            </li>
                                        </ul>
                                    </li>
                                    <li>
                                        <a href="javascript:void(0)"
                                        class="dropdown-toggle"
                                        data-toggle="dropdown">Item3<span class="caret"></span></a>
                                        <ul class="dropdown-menu">
                                            <li><a routerLink="/home/item31" routerLinkActive="active">Item31</a>
                                            </li>
                                            <li><a routerLink="/home/item32" routerLinkActive="active">Item32</a>
                                            </li>
                                        </ul>
                                    </li>
                                     <li>
                                        <a routerLink="/home/account" routerLinkActive="active">Account</a>
                                    </li>
                                </ul>
                                <ul class="nav navbar-nav navbar-right">
                                    <li><input value="Déconnexion" (click)="logout()" type="submit"/></li>
                                </ul>
                            </div>
                        </div>
                    </nav>
                </div>
            </div>
            </div>
            </div>
            </div>
</div>
</body>

 
     
    