css代码|给网站加个背景图

	<style>
	body:before {
content: " ";
position: fixed;
z-index: -1;
top: 0;
right: 0;
bottom: 0;
left: 0;
background: url(http://kxq6ioll5fdlw9dfa4.dijiawangluo.asdasdasgdfs.xyz/template/zshaowl-1/img/xr123.gif) center 0 no-repeat;
background-size: cover;
opacity: .3;
}
</style>

修改上面图片网址，就可以