Bootstrap响应式导航由768px变成992px

<!--响应式导航部分-->
<header role="banner">
    <nav role="navigation" class="navbar navbar-static-top navbar-default">
        <div class="container ">
            <div class="navbar-header">
                <!--设置手风琴式的navbar，然后类navbar-toggle包装在屏幕大于992px，隐藏-->
                <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#navbar-collapse">
                    <!--这里的span.icon-bar 是用来在按钮中画三条线-->
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                </button>
                <a class="navbar-brand" href="/go.html?url=index.html"><img src="img/logo.png" alt="Bootstrappin'" width="120"></a>
                <!--这里的商标图一定要设置宽度-->
            </div>
            <!--这里的类collapse保证默认包裹的菜单是隐藏的，如果 替换为 in 则显示-->
            <div class="navbar-collapse collapse" id="navbar-collapse">
                <ul class="nav navbar-nav">
                    <li class="active"><a href="/go.html?url=index.html">
                        <span class="icon fa fa-home "></span> Home</a></li>
                    <li><a href="/go.html?url=#">
                       <span class="icon fa fa-desktop"></span> Portfolio</a></li>
                    <li><a href="/go.html?url=#">
                        <span class="icon fa fa-group "></span> Team</a></li>
                    <li><a href="/go.html?url=#">
                        <span class="icon fa fa-envelope "></span> Contact</a></li>
                </ul>
            </div><!--/.nav-collapse -->
        </div><!--/.container -->
    </nav>
</header><!--响应式导航部分-->
<header role="banner">
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