側邊欄在響應式設計中起到很大的作用，當螢幕小到手機的螢幕時，能夠自適應螢幕大小的側邊欄固然能夠為網站新增色彩，那麼在Bootstrap的框架中提供了導航條和下拉選單的元件，詳情請自行到官網Bootstrap的文件檢視，這裡就不作介紹了。

   本文是將其中的導航條和下拉選單進行結合，然後設計並改進了側邊欄的製作。

html:

<div class="container">
    <nav class="navbar navbar-default mynavbar">
        <div class="container-fluid">
            <!--按鈕-->
            <div class="navbar-header">
                <button type="button" class="navbar-toggle collapsed btn-sider" data-toggle="collapse" data-target="#side-menu" aria-expanded="false">
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                </button>
            </div>

            <!-- 導航條內容 -->
            <div class="collapse navbar-collapse" id="side-menu">
                <ul class="nav navbar-nav" id="side-item">
                    <li><a href="#">後端開發</a></li>
                    <li><a href="#">資料庫</a></li>
                    <li class="dropdown">
                        <a href="#" class="dropdown-toggle" id="web-item" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false">前端開發 <span class="caret"></span></a>
                        <!--下拉選單按鈕-->
                        <ul class="dropdown-menu">
                            <li><a href="#">HTML/CSS</a></li>
                            <li><a href="#">JavaScript</a></li>
                            <li><a href="#">jQuery</a></li>
                            <li><a href="#">Bootstrap</a></li>
                            <li><a href="#">node.js</a></li>
                        </ul>
                    </li>
                    <li><a href="#">移動開發</a></li>
                    <li><a href="#">視覺設計</a></li>
                    <li><a href="#">雲端計算</a></li>
                </ul>
            </div>
        </div>
    </nav>
</div>
 

        .mynavbar{
            background-color: #fff;
            border:none;
        }
        .navbar-header,#side-item{
            background-color: #0b3558;
        }

        #side-menu>ul>li>a{
            color:#fff;
            font-size: 18px;
            font-family: "Microsoft Yahei", Helvetica, sans-serif, Lato;
        }
        #side-menu>ul{
            width: 100%;
        }
        #side-menu>ul>li{
            text-align: center;
            width: 16%;
            margin-left: 5px;
        }
        #side-menu .dropdown-menu {
            border: none;
            -webkit-box-shadow: 0 6px 12px rgba(0,0,0,.175);
            box-shadow: 0 6px 12px rgba(0,0,0,.175);
        }
        #side-item .dropdown-menu>li>a:focus, .dropdown-menu>li>a:hover,#side-item>li>a:focus,#side-item >li>a:hover {
            color: #24b0ff;
            text-decoration: none;
            background-color: transparent;
        }
        .btn-sider{
            float: left;
            border:none;
            outline: none;
            margin-left: 10px;
        }
        .mynavbar .btn-sider .icon-bar{
            background-color:#fff;
            width:23px;
            height:3px;
        }
        .mynavbar .btn-sider:focus, .mynavbar .btn-sider:hover {
            background-color: transparent;
        }
        @media (max-width: 768px) {
            .container {
                padding-left: 0px;
            }
            #side-menu{
                border: none;

            }
            #side-item{
                background: rgba(43, 54, 67, 0.97);
            }
            #side-menu>ul {
                margin-top: 0px;
                margin-right: 0px;
                margin-left: -15px;
                margin-bottom: 0px;
                width: 40%;
                height: 999px;
            }
            #side-menu>ul>li {
                text-align: left;
                width:100%;
                margin-left:0px;
            }
            #side-menu>ul>li a{
                font-size:16px;
            }
            #side-item>li>a:focus,#side-item >li>a:hover,#side-item .dropdown-menu>li>a:focus, .dropdown-menu>li>a:hover{
                background-color: #38a99c;
                color:#fff;
            }
            #side-menu .dropdown-menu{
                box-shadow:none;
            }
            #side-menu .dropdown-menu li a{
                padding-top:10px;
                color:#fff;
            }
        }