在web 客户端，通过css + div模拟了一个 (parent)drop down list，其内部嵌套另一个（child）drop down list， 想将内部子下拉菜单取值后的内容传给外层的drop down list后输出，但不知如何修改代码，求大家帮忙指点一下。以下是代码：
demo.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Custom Drop-Down List Styling</title>
<link rel="stylesheet" type="text/css" href="style.css" />
<link href='http://fonts.googleapis.com/css?family=Lato:300,400,700' rel='stylesheet' type='text/css' />
<script type="text/javascript" src="modernizr.custom.79639.js"></script>
<noscript><link rel="stylesheet" type="text/css" href="noJS.css" /></noscript>
</head>
<body>
<div class="container">
<!-- Codrops top bar -->
<div class="codrops-top"></div><!--/ Codrops top bar -->
<header>
<h1> </h1>
<h2> </h2>
<nav class="codrops-demos"></nav>
</header>
<section class="main">
<div class="wrapper-demo">
<div id="dd" class="wrapper-dropdown-1" tabindex="1">
<span>Select Contact</span>
<ul class="dropdown" tabindex="1">