是我的代碼有問題么？為什么做出來的效果跟老師演示的不一樣呀？
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>靜態頁面的實現</title>
<style type="text/css">
h3 ul {margin: 0;padding: 0;}
ul{list-style: none;}
li h3{font-size: 14px;font-weight: 400}
li{display: block;height: 31px;line-height: 31px;overflow:hidden;border-bottom: 1px solid #dedede}
li i{background: url(sidebar.png);display: inline;width: 30px;height: 24px;float: left;margin: 30px 10px 0 0;}
.cat{width: 150px;background: #f8f8f8;border: 1px
solid #bbb;}
.cat1 i{background-position: 0 0;}
.cat2 i{background-position: 0 -24px;}
</style>
2015-11-04
h3,ul,li{margin: 0;padding: 0;}
ul{list-style: none;}
li h3{font-size: 14px;font-weight: 400}
li{display: block;height: 31px;line-height: 31px;overflow:hidden;border-bottom: 1px solid #dedede}
li i{background: url(img/sidebar.png);display: inline;width: 30px;height: 24px;float: left;margin: 5px 5px 0 5px;}
.cat{width: 150px;background: #f8f8f8;border: 1px solid #bbb;}
.chart-1 i{background-position: 0 0;}
.chart-2 i{background-position: 0 -24px;}
得這么寫