一个常见下拉菜单的样式可恶的一体化小三角纯css手写解决

May 8, 2017

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3297 words

<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title>下拉菜单</title>
        <style>
            .select {
                margin: 50px 500px;
                width: 180px;
                text-align: center;
            }
            
            .select a {
                color: #fff;
                text-decoration: none;
            }
            
            .select ul,
            .select li {
                margin: 0;
                padding: 0;
                list-style: none;
            }
            
            .select span {
                line-height: 46px;
                background-color: #41b1d9;
                display: block;
                margin-bottom: 20px;
                position: relative;
                z-index: 2;
                border-radius: 5px;
                -webkit-transition: all .2s ease-in;
                transition: all .2s ease-in;
            }
            
            .select span a:after{
                content: " ";
                display: inline-block;
                width: 0;
                height: 0;
                font-size: 0;
                line-height: 0;
                border-bottom: solid 6px #fff;
                border-left: solid 4px transparent;
                border-right: solid 4px transparent;
                vertical-align: 1px;
                margin-left: 10px;
                -webkit-transition: all .2s ease-in;
                transition: all .2s ease-in;
            }
            
            /*给以整体的阴影和圆角 但是不能overflow*/
            .drop {
                left: 0;
                right: 0;
                top: -9999px;
                box-shadow: 0 0 2px 0 rgba(0, 0, 0, 0.2);
                border-radius: 5px;
                position: absolute;
                z-index: 1;
                -webkit-transform: translateY(-50px);
                transform: translateY(-50px);
                opacity: 0;
                -webkit-transition: all .2s ease-in;
                transition: all .2s ease-in;
            }
            
            /*给送个下拉助攻*/
            .select:hover span{
                background-color: #1f93bc;
            }
            
            .select:hover span a:after{
                -webkit-transform: rotate(180deg);
                transform: rotate(180deg);
            }
            
            .select:hover .drop{
                position: static;
                opacity: 1;
                -webkit-transform: translateY(0);
                transform: translateY(0);
            }
            
            /*一个很重要的三角形*/
            .drop li:first-child:before {
                content: " ";
                font-size: 0;
                line-height: 0;
                margin: 0 auto;
                display: block;
                box-shadow: 0 0 2px 0 rgba(0, 0, 0, 0.2); /*配合整体一样的投影*/
                background-color: #fff;
                width: 10px;
                height: 10px;
                -webkit-transform: rotate(45deg); 
                transform: rotate(45deg); /*一个正方形倾斜四十五度就是三角了  但是要把下半部分藏起来*/
                position: relative;
                top: -5px; /*果断的露出上半部分*/
                z-index: 1; /*果断的隐藏下半部分*/
                -webkit-transition: all .2s ease-in;
                transition: all .2s ease-in;
            }
            .drop li a {
                color: #888;
                line-height: 46px;
                border-bottom: solid 1px #eee;
                font-size: 14px;
                display: block;
                background-color: #fff; /*要有背景色才能盖住呀*/
                position: relative;
                z-index: 2; /*这里很重要 要挡住三角形的下半部分*/
                -webkit-transition: all .2s ease-in;
                transition: all .2s ease-in;
            }

            /*以下两块 控制第一个和最后一个LI要圆角  因为最外边的div没有overflow 也不可以overflow*/
            .drop li:first-child a{
                border-top-left-radius: 5px;
                border-top-right-radius: 5px;
                margin-top: -10px;
            }
            .drop li:last-child a{
                border-bottom-left-radius: 5px;
                border-bottom-right-radius: 5px;
                border-bottom: none;
            }
            
            /*hover事件给了li  先改变三角 再改变a*/
            .drop li:hover:before{
                background-color: #41b1d9;
            }
            .drop li:hover a {
                background-color: #41b1d9;
                color: #fff;
            }
        </style>
    </head>

    <body>
        <div class="select">
            <span><a href="javascript:void(0);">鼠标浮上来</a></span>
            <div class="drop">
                <ul>
                    <li>
                        <a href="javascript:void(0);">下拉菜单一</a>
                    </li>
                    <li>
                        <a href="javascript:void(0);">下拉菜单二</a>
                    </li>
                    <li>
                        <a href="javascript:void(0);">下拉菜单三</a>
                    </li>
                    <li>
                        <a href="javascript:void(0);">下拉菜单四</a>
                    </li>
                </ul>
            </div>
        </div>
    </body>

</html>

一个常见下拉菜单的样式可恶的一体化小三角纯css手写解决