css3左侧菜单自适应高度默认收缩起来，只显示图标，当鼠标进入菜单区域，滑动展开显示菜单名称和图标效果。

使用方法

1、head引入css文件

<link rel="stylesheet" href="css/font-awesome.css">
<link rel="stylesheet" href="css/style.css">

2、body引入部分

<nav class="menu-wrap">
	<div class="menu">
		<ul>
			<li>
				<a href="">
					<i class="fa fa-home fa-lg"></i>
					<span class="nav-text">首页</span>
				</a>
			</li>
			<li>
				<a href="">
					<i class="fa fa-user fa-lg"></i>
					<span class="nav-text">登录</span>
				</a>
			</li>
			<li>
				<a href=" ">
					<i class="fa fa-envelope-o fa-lg"></i>
					<span class="nav-text">联系</span>
				</a>
			</li>
			<li>
				<a href=" ">
					<i class="fa fa-heart-o fa-lg"></i>
					<span class="nav-text">收藏</span>
				</a>
			</li>
			</li>
			<li class="darkerlishadow">
				<a href=" ">
					<i class="fa fa-clock-o fa-lg"></i>
					<span class="nav-text">新闻</span>
				</a>
			</li>

			<li class="darkerli">
				<a href=" ">
					<i class="fa fa-desktop fa-lg"></i>
					<span class="nav-text">技术</span>
				</a>
			</li>
			<li class="darkerli">
				<a href=" ">
					<i class="fa fa-plane fa-lg"></i>
					<span class="nav-text">旅行</span>
				</a>
			</li>
			<li class="darkerli">
				<a href=" ">
					<i class="fa fa-shopping-cart"></i>
					<span class="nav-text">购物</span>
				</a>
			</li>
			<li class="darkerli">
				<a href=" ">
					<i class="fa fa-microphone fa-lg"></i>
					<span class="nav-text">娱乐</span>
				</a>
			</li>
			<li class="darkerli">
				<a href=" ">
					<i class="fa fa-flask fa-lg"></i>
					<span class="nav-text">工具</span>
				</a>
			</li>
			<li class="darkerli">
				<a href=" ">
					<i class="fa fa-picture-o fa-lg"></i>
					<span class="nav-text">设计</span>
				</a>
			</li>
			<li class="darkerli">
				<a href=" ">
					<i class="fa fa-align-left fa-lg"></i>
					<span class="nav-text">杂志
					</span>
				</a>
			</li>
			<li class="darkerli">
				<a href=" ">
					<i class="fa fa-gamepad fa-lg"></i>
					<span class="nav-text">游戏</span>
				</a>
			</li>
			<li class="darkerli">
				<a href=" ">
					<i class="fa fa-glass fa-lg"></i>
					<span class="nav-text">生活
					</span>
				</a>
			</li>
			<li class="darkerlishadowdown">
				<a href=" ">
					<i class="fa fa-rocket fa-lg"></i>
					<span class="nav-text">娱乐</span>
				</a>
			</li>
			<li>
				<a href=" ">
					<i class="fa fa-question-circle fa-lg"></i>
					<span class="nav-text">帮助</span>
				</a>
			</li>
			<li>
				<a href=" ">
					<i class="fa fa-lightbulb-o fa-lg"></i>
					<span class="nav-text">博客</span>
				</a>
			</li>
		</ul>
	</div>
</nav>

资源出处：https://www.moyublog.com/codes/9351.html