如果你碰巧在现代浏览器中碰到这个话题，你可以使用伪类:after来做任何与后台相关的事情。

.container:after{
    content:"";
    position:absolute;
    right:20px;
    background:url(http://lorempixel.com/400/200) no-repeat right bottom;
}

这个CSS会把背景放在“”的右下角。元素的右侧有20px的空间。

看看这个小提琴，例如http://jsfiddle.net/h6K9z/226/

对大家都好

background: url('../images/bg-menu-dropdown-top.png') left 20px top no-repeat !important;

据我所知，CSS规范并没有提供您所要求的内容，当然，除了CSS表达式之外。除去你不想使用表达式或Javascript的假设，我看到了三个hack的解决方案:

Make sure your background image matches the size of the container (at least in width) and set background-repeat: repeat or repeat-x if only the width is equalized. Then, having something appear x pixels from the right is as simple as background-position: -5px 0px. Using percentages for background-position exhibits special behaviour that is better seen than described here. Give it a shot. Essentially, background-position: 90% 50% will make the right edge of the background image line up 10% away from the right edge of the container. Create a div containing the image. Explicitly set the position of the containing element position: relative if not already set. Set the image container to position: absolute; right: 10px; top: 10px;, obviously adjusting the final two as you see fit. Place the image div container into the containing element.

如果你只想指定x轴，你可以这样做:

background-position-x: right 100px;

试试这个:

#myelement {
  background-position: 100% 50%;
  margin-right: 5px;
}

注意上面的代码会将整个元素(不仅仅是背景图像)向右移动5px。这对你的案子来说可能没问题。

这个问题已经被问到很久了，但我刚刚遇到了这个问题，我是这样做的:

background-position:95% 50%;