<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Html和CSS的关系</title>
<style type="text/css">
h1{
font-size:12px;
color:#930;
text-align:center;
}
</style>
</head>
<body>
<h1>Hello World!</h1>
</body>
</html>
h1{
font-size:12px;
color:#930;
text-align:center;
}
使得h1标签里的字体大小（ font-size）为12px