大图片根据分辨率自适应宽度仍居中显示

width: 100%;
background-position: 50% 50%;

<style>
body {
background-repeat: no-repeat;
width: 100%;
background-position-x: 50%;
background-position-y: 118px;
background-image:url(@Url.Image("/XXX/XX.jpg"));
}
.book {
margin: 0 auto;
width: 960px;
height: 700px;
position: relative;
}
</style>

<div class="book"></div>