XML与CSS ID选择符的使用

ID.xml
<?xml version="1.0" encoding="utf-8"?>
<?xml-stylesheet type="text/css" href="ID.css"?>
<bookdetail>
<book class="A" id="B1">
<author>曹雪芹</author>
<title>红楼梦</title>
<price>60.00</price>
</book>
<book class="A" id="B2">
<author>罗贯中</author>
<title>三国演义</title>
<price>20.00</price>
</book>
<book class="M" id="B3">
<author>琼瑶</author>
<title>一帘幽梦</title>
<price>20.00</price>
</book>
</bookdetail>
ID.css
@charset "utf-8";
/* CSS Document */
bookdetail
{
display:block
}
book#B3
{
font-weight:bold;
color:red
}
book
{
display:block
}
author
{
font-style:italic
}