我找到了一个更优雅的解决方案，结合“内联块”来避免使用float和俗气的clear:两者。它仍然需要嵌套的divs，这不是很语义，但它只是工作…

div.outer{
    display:inline-block;
    position:relative;
    left:50%;
}

div.inner{
    position:relative;
    left:-50%;
}

希望能有所帮助!

恐怕唯一不显式指定宽度的方法是使用(gasp)表。

将这个CSS添加到product_container类中

    margin: 0px auto;
    padding: 0px;
    border:0;
    width: 700px;

使用css3 flexbox与justify-content:center;

    <div class="row">
         <div class="col" style="background:red;">content1</div>
          <div class="col" style="">content2</div>
    </div>


.row {
    display: flex; /* equal height of the children */
    height:100px;
    border:1px solid red;
    width: 400px;
    justify-content:center;
}

我发现了一个有趣的解决方案，我正在制作滑块，必须将滑块控制居中，我这样做，工作很好。您也可以添加相对位置到父和移动子位置垂直。看看http://jsfiddle.net/bergb/6DvJz/

CSS:

#parent{
        width:600px;
        height:400px;
        background:#ffcc00;
        text-align:center;
    }

#child{
        display:inline-block;
        margin:0 auto;
        background:#fff;
    }  

HTML:

<div id="parent">
    <div id="child">voila</div>
</div>

2015年2月27日更新:我最初的答案不断被投票，但现在我通常使用@bobince的方法。

.child { /* This is the item to center... */
  display: inline-block;
}
.parent { /* ...and this is its parent container. */
  text-align: center;
}

出于历史目的，我原来的帖子是:

您可能想尝试这种方法。

<div class="product_container">
    <div class="outer-center">
        <div class="product inner-center">
        </div>
    </div>
    <div class="clear"/>
</div>

下面是匹配的样式:

.outer-center {
    float: right;
    right: 50%;
    position: relative;
}
.inner-center {
    float: right;
    right: -50%;
    position: relative;
}
.clear {
    clear: both;
}

JSFiddle

The idea here is that you contain the content you want to center in two divs, an outer one and an inner one. You float both divs so that their widths automatically shrink to fit your content. Next, you relatively position the outer div with it's right edge in the center of the container. Lastly, you relatively position the inner div the opposite direction by half of its own width (actually the outer div's width, but they are the same). Ultimately that centers the content in whatever container it's in.

如果你依赖于你的“product”内容来调整“product_container”的高度，你可能需要在结尾使用空的div。