Bootstrap教學－Navbar導覽列選單太長，自動隱藏選單並出現選單按鈕

@media (max-width: 991px) {
    .navbar-header {
        float: none;
    }
    .navbar-toggle {
        display: block;
    }

    .navbar-collapse {
        border-top: 1px solid transparent;
        box-shadow: inset 0 1px 0 rgba(255,255,255,0.1);
    }
    .navbar-collapse.collapse {
        display: none!important;
    }
    .navbar-nav>li {
        float: none;
    }
    .navbar-nav>li>a {
        padding-top: 10px;
        padding-bottom: 10px;
    }
    .navbar-text {
        float: none;
        margin: 15px 0;
    }
    /* since 3.1.0 */
    .navbar-collapse.collapse.in {
        display: block!important;
    }
    .collapsing {
        overflow: hidden!important;
    }
}