<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
<style>
<!-- 某一类标签的样式 -->
div {background-color:#b0c4de;}
p { font-size:24px; text-align:left; color:red;}
<!-- 根据标签中的 class 属性来设置标签的样式 -->
.master {font-size:18px;color:red; text-align:center;}
.item { border-style:red;}
<!-- 根据某一类标签的 class 属性来设置标签元素样式 -->
p.item { color:black; font-size:14px;}
div.item { text-align:center;font-size:; color:blue;width:100px;}
<!-- id选择器样式 -->
#dvi { color:black;font-size:24px; width:200px;margin: auto;}
#title { font-size:28px;text-align:center; }
</style>
</head>
<body>
<div class="master">
<div id="title">
welcome to java web!
</div>
<p class="item">css style test h2</p>
<div class="item">css style test h2</div>
<div id="dvi">css style test div </div>
</div>
</body>
</html>