Examples

        <%= navbar header => ['The brand', ['#'], hamburger, toggler => 'bs-example-navbar-collapse-1'], [] %>

        <nav class="navbar navbar-default">
            <div class="container-fluid">
                <div class="navbar-header">
                    <button class="collapsed navbar-toggle" data-target="#bs-example-navbar-collapse-1" data-toggle="collapse" type="button">
                        <span class="icon-bar"></span>
                        <span class="icon-bar"></span>
                        <span class="icon-bar"></span>
                    </button>
                    <a class="navbar-brand" href="#">The brand</a>
                </div>
            </div>
        </nav>

        <%= navbar html_header => qq{
                <div class="navbar-header">
                    <button class="collapsed navbar-toggle" data-target="#bs-example-navbar-collapse-1" data-toggle="collapse" type="button">
                        <span>Expand</span>
                    </button>
                    <a class="navbar-brand" href="#">The brand</a>
                </div>
        }, [] %>

        <nav class="navbar navbar-default">
            <div class="container-fluid">
                <div class="navbar-header">
                    <button class="collapsed navbar-toggle" data-target="#bs-example-navbar-collapse-1" data-toggle="collapse" type="button">
                        <span>Expand</span>
                    </button>
                    <a class="navbar-brand" href="#">The brand</a>
                </div>
            </div>
        </nav>

By using `html_header` you can specify an entirely customized header.

        <%= navbar header => ['The brand', ['#'], hamburger, toggler => 'bs-example-navbar-collapse-1'],
                   [
                        {
                            nav => [
                                [
                                    ['Link', ['#'] ],
                                    ['Another link', ['#'], active ],
                                    {
                                        button => ['Menu', ['#'], caret ],
                                        items => [
                                            ['Choice 1', ['#'] ],
                                            ['Choice 2', ['#'] ],
                                            [],
                                            ['Choice 3', ['#'] ],
                                        ]
                                    }
                                ]
                            ]
                        }
                   ]
        %>

        <nav class="navbar navbar-default">
            <div class="container-fluid">
                <div class="navbar-header">
                    <button class="collapsed navbar-toggle" data-target="#bs-example-navbar-collapse-1" data-toggle="collapse" type="button">
                        <span class="icon-bar"></span>
                        <span class="icon-bar"></span>
                        <span class="icon-bar"></span>
                    </button>
                    <a class="navbar-brand" href="#">The brand</a>
                </div>
                <div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
                    <ul class="nav navbar-nav">
                        <li><a href="#">Link</a></li>
                        <li class="active"><a href="#">Another link</a></li>
                        <li class="dropdown">
                            <a class="dropdown-toggle" data-toggle="dropdown" href="#">Menu <span class="caret"></span></a>
                            <ul class="dropdown-menu">
                                <li><a href="#">Choice 1</a></li>
                                <li><a href="#">Choice 2</a></li>
                                <li class="divider"></li>
                                <li><a href="#">Choice 3</a></li>
                            </ul>
                        </li>
                    </ul>
                </div>
            </div>
        </nav>