最后，我不想设置第二个÷>的宽度。因为我需要标记以不同的宽度工作。

样品标记在http://jsfiddle.net/rhEyM/以下。

CSS

.left-div {
    float: left;
    width: 100px;
    height: 20px;
    margin-right: 8px;
    background-color: linen;
}
.right-div {
    float: left;
    margin-left: 108px;
    background-color: skyblue;
}​

HTML

<div class="left-div">
    &nbsp;
</div>
<div class="right-div">
    My requirements are <b>[A]</b> Content in the two divs should line
    up at the top,<b>[B]</b> Long text in right-div should not wrap
    underneath left-div,and <b>[C]</b> I do not want to specify a
    width of right-div. I don't want to set the width of right-div
    because this markup needs to work within different widths.
</div>