<style>

.box{overflow: hidden;resize: vertical;width: 1000px;}

.orange,.green{margin-bottom: -600px;padding-bottom: 600px;line-height: 50px;width:50%;}

.orange{background: orange;float: left;}

.green{background: green;float: left;}

</style>

<div class="box">

<nav class="orange">

<h3>导航1</h3>

</nav>

<section class="green">

模块1

</section>

<section class="green">

模块1

</section>

<section class="green">

模块1

</section>

</div>