怎样对齐层中的多个列层

[lymlx]

<div style='width:700px'>
<div style='width:700px'>
<div id='1' style='height:100'>1</div>
<div id='2' style='height:150'>2</div>
<div id='3' style='height:120'>3</div>
<div id='4' style='height:180'>4</div>
</div>
</div>

怎样对齐1,2,3,4的顶部.

[Giberson1]

将代码改成如下：

<div style='width:700px'>
<div style='width:700px'>
<div id='1' style='height:100;float:left;border: 1px solid red'>1</div>
<div id='2' style='height:150;float:left;border: 1px solid red'>2</div>
<div id='3' style='height:120;float:left;border: 1px solid red'>3</div>
<div id='4' style='height:180;float:left;border: 1px solid red'>4</div>
</div>
</div>

[Giberson1]

显示结果如下：

[Giberson1]