不清理

布局看上去会像这样：

几个列漂在footer上方，footer环绕着列。这可不对！

清理

方法相当简单，我们只需要在三个列后面加上一个<div>，如下：

<div id="content">  
          
    <div class="column1">  
      
        <h2>a sleek design</h2>  
          
        <p>This design was produced for a photoshop and web development tutorial.  You can see the first part up at PSDTUTS.com where you learn how to create a beautiful, but simple design using an abstract background and type.</p>  
        <p>The second part of the tutorial is available via NETTUTS.com where we do a quick build of the PSD into a viable, working HTML/CSS site.</p>  
        <p>This design was produced for a photoshop and web development tutorial.  You can see the first part up at PSDTUTS.com where you learn how to create a beautiful, but simple design using an abstract background and type.</p>  
        <p>The second part of the tutorial is available via NETTUTS.com where we do a quick build of the PSD into a viable, working HTML/CSS site.</p>  
  
    </div>  
    <div class="column2">  
          
        <h2>tutorials</h2>  
      
        <p>This design was produced for a photoshop and web development tutorial.  You can see the first part up at PSDTUTS.com where you learn how to create a beautiful, but simple design using an abstract background and type.</p>  
        <p>The second part of the tutorial is available via NETTUTS.com where we do a quick build of the PSD into a viable, working HTML/CSS site.</p>  
        <p>This design was produced for a photoshop and web development tutorial.  You can see the first part up at PSDTUTS.com where you learn how to create a beautiful, but simple design using an abstract background and type.</p>  
        <p>The second part of the tutorial is available via NETTUTS.com where we do a quick build of the PSD into a viable, working HTML/CSS site.</p>  
  
  
    </div>  
    <div class="column3">  
      
        <h2>recent work</h2>  
  
        <p>This design was produced for a photoshop and web development tutorial.  You can see the first part up at PSDTUTS.com where you learn how to create a beautiful, but simple design using an abstract background and type.</p>  
        <p>The second part of the tutorial is available via NETTUTS.com where we do a quick build of the PSD into a viable, working HTML/CSS site.</p>  
        <p>This design was produced for a photoshop and web development tutorial.  You can see the first part up at PSDTUTS.com where you learn how to create a beautiful, but simple design using an abstract background and type.</p>  
        <p>The second part of the tutorial is available via NETTUTS.com where we do a quick build of the PSD into a viable, working HTML/CSS site.</p>  
  
      
    </div>  
      
    <div style="clear:both"></div>  
      
</div>  

看到底部的<div style="clear:both"></div>了吗？只用一个声明清理那三个列的空<div>，就解决了我们的问题。