CSS三欄佈局探討－中間固定寬度兩邊自適應寬度

下面和大家一起探討和學習了一種用p+css進行的三列（三欄）佈局，而且是中間固定左右兩邊自適應寬度，聽起來蠻有意思的。因為以前只是碰到過，左右兩列固定而中間自適應的運用 今天早上在阿當大俠的編寫高質量前端代碼群中與幾位朋友一起探討和學習了一種用p+css進行的三列（三欄）佈局，而且是中間固定左右兩邊自適應寬度，聽起來蠻有意思的。因為以前只是碰到過，左右兩列固定而中間自適應的運用。於是思考一下馬上敲起了鍵盤自己實戰了一下，接著與大家一起測試，還是通過了各瀏覽器的考驗，為了方便自己以後好查閱，也想讓不知道的朋友一起學習一下這樣的佈局，特整理了一下程式碼，貼上來與大家一起分享和學習。

在講這種佈局之前，我還想和大家一起回想一下三列佈局中的另一種，就是左右兩列固定，中間自適應寬度。這種佈局方法，網路上問Ｇ爸和度娘一定會有一大堆，但我還是要重複說說，方便自己今後查閱，記性太差，沒辦法。別的先不說了，就開始進入主題吧。對於兩邊固定中間一列自適應的佈局方法，我最早使用的是絕對定位法。先看程式碼

程式碼如下:

<span class="tag"><<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span> <span class="attribute" style="color:rgb(181,137,0)">id</span>=<span class="value" style="color:rgb(42,161,152)">"left"</span>></span>左边栏<span class="tag"></<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span>></span> 
<span class="tag"><<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span> <span class="attribute" style="color:rgb(181,137,0)">id</span>=<span class="value" style="color:rgb(42,161,152)">"right"</span>></span>右边栏<span class="tag"></<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span>></span> 
<span class="tag"><<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span> <span class="attribute" style="color:rgb(181,137,0)">id</span>=<span class="value" style="color:rgb(42,161,152)">"main"</span>></span>主内容<span class="tag"></<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span>></span>

比如說，我左右兩列都是220px，中間寬度自適應，那麼我們使用絕對定位實作的方法是這樣的

:

程式碼如下

這種方法是最簡單，也是麻煩最多的，如果中間欄含有最小寬度限制，或是含有寬度的內部元素，當瀏覽器寬度小到一定程度，會發生層重疊的情況。我個人現在不在建議使用這種佈局。


第二種方法採用的是浮動佈局
這種方法和上面的絕對定位方法很相似，只不過這裡採用的是浮動，而不是絕對定位，先來看其html代碼

代碼如下:

<span class="tag">html</span>,<span class="tag">body</span> <span class="rules">{ 
<span class="rule"><span class="attribute" style="color:rgb(181,137,0)">margin</span>:<span class="value"><span class="number" style="color:rgb(42,161,152)">0</span>;</span></span> 
<span class="rule"><span class="attribute" style="color:rgb(181,137,0)">padding</span>:<span class="value"><span class="number" style="color:rgb(42,161,152)">0</span>;</span></span> 
<span class="rule"><span class="attribute" style="color:rgb(181,137,0)">height</span>:<span class="value"> <span class="number" style="color:rgb(42,161,152)">100</span>%;</span></span> 
<span class="rule">}</span></span> 
<span class="id" style="color:rgb(38,139,210)">#left</span>, 
<span class="id" style="color:rgb(38,139,210)">#right</span> <span class="rules">{ 
<span class="rule"><span class="attribute" style="color:rgb(181,137,0)">position</span>:<span class="value"> absolute;</span></span> 
<span class="rule"><span class="attribute" style="color:rgb(181,137,0)">top</span>:<span class="value"><span class="number" style="color:rgb(42,161,152)">0</span>;</span></span> 
<span class="rule"><span class="attribute" style="color:rgb(181,137,0)">width</span>:<span class="value"> <span class="number" style="color:rgb(42,161,152)">220</span>px;</span></span> 
<span class="rule"><span class="attribute" style="color:rgb(181,137,0)">height</span>:<span class="value"> <span class="number" style="color:rgb(42,161,152)">100</span>%;</span></span> 
<span class="rule">}</span></span> 
<span class="id" style="color:rgb(38,139,210)">#left</span> <span class="rules">{ 
<span class="rule"><span class="attribute" style="color:rgb(181,137,0)">left</span>:<span class="value"><span class="number" style="color:rgb(42,161,152)">0</span>;</span></span> 
<span class="rule">}</span></span> 
<span class="id" style="color:rgb(38,139,210)">#right</span> <span class="rules">{ 
<span class="rule"><span class="attribute" style="color:rgb(181,137,0)">right</span>:<span class="value"><span class="number" style="color:rgb(42,161,152)">0</span>;</span></span> 
<span class="rule">}</span></span> 
<span class="id" style="color:rgb(38,139,210)">#main</span> <span class="rules">{ 
<span class="rule"><span class="attribute" style="color:rgb(181,137,0)">margin</span>:<span class="value"> <span class="number" style="color:rgb(42,161,152)">0</span> <span class="number" style="color:rgb(42,161,152)">230</span>px;</span></span> 
<span class="rule"><span class="attribute" style="color:rgb(181,137,0)">height</span>:<span class="value"> <span class="number" style="color:rgb(42,161,152)">100</span>%;</span></span> 
<span class="rule">}</span></span>

這種方法我利用的就是浮動原理，左右定寬度分別進行左浮動和右浮動，此時主內容列（中間列沒有定度）主會自動插入到左右兩列的中間，最要注意的一點是，中間欄位一定要放在左右兩列的後面，如上面的html程式碼所示，下面我們一起來看看其css樣式是怎麼實現的

程式碼如下:

<span class="tag"><<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span> <span class="attribute" style="color:rgb(181,137,0)">id</span>=<span class="value" style="color:rgb(42,161,152)">"left"</span>></span>left <span class="tag"></<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span>></span> 
<span class="tag"><<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span> <span class="attribute" style="color:rgb(181,137,0)">id</span>=<span class="value" style="color:rgb(42,161,152)">"right"</span>></span>right<span class="tag"></<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span>></span> 
<span class="tag"><<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span> <span class="attribute" style="color:rgb(181,137,0)">id</span>=<span class="value" style="color:rgb(42,161,152)">"main"</span>></span>mian<span class="tag"></<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span>></span>

是不是好簡單一種方法呀，大家可以在本地機子上動手測試一下，效果如下所示：

 

第三種方法：負的margin
使用這種方法就稍微複雜了一些了，使用的是負的margin值，而且html標籤也增加了，先來看其代碼吧

代碼如下:

<span class="id" style="color:rgb(38,139,210)">#left</span>, 
<span class="id" style="color:rgb(38,139,210)">#right</span> <span class="rules">{ 
<span class="rule"><span class="attribute" style="color:rgb(181,137,0)">float</span>:<span class="value"> left;</span></span> 
<span class="rule"><span class="attribute" style="color:rgb(181,137,0)">width</span>:<span class="value"> <span class="number" style="color:rgb(42,161,152)">220</span>px;</span></span> 
<span class="rule"><span class="attribute" style="color:rgb(181,137,0)">height</span>:<span class="value"> <span class="number" style="color:rgb(42,161,152)">200</span>px;</span></span> 
<span class="rule"><span class="attribute" style="color:rgb(181,137,0)">background</span>:<span class="value"> blue;</span></span> 
<span class="rule">}</span></span> 
<span class="id" style="color:rgb(38,139,210)">#right</span><span class="rules">{ 
<span class="rule"><span class="attribute" style="color:rgb(181,137,0)">float</span>:<span class="value"> right;</span></span> 
<span class="rule">}</span></span> 
<span class="id" style="color:rgb(38,139,210)">#main</span> <span class="rules">{ 
<span class="rule"><span class="attribute" style="color:rgb(181,137,0)">margin</span>:<span class="value"> <span class="number" style="color:rgb(42,161,152)">0</span> <span class="number" style="color:rgb(42,161,152)">230</span>px;</span></span> 
<span class="rule"><span class="attribute" style="color:rgb(181,137,0)">background</span>:<span class="value"> red;</span></span> 
<span class="rule"><span class="attribute" style="color:rgb(181,137,0)">height</span>:<span class="value"> <span class="number" style="color:rgb(42,161,152)">200</span>px;</span></span> 
<span class="rule">}</span></span>

從上面的Html代碼中我們可以明顯得看出，在main,left ,right三個p內部我都增加了一個p，那麼他們起了什麼樣的作用呢，大家從下在的CSS中可以明顯的體會出來。 

程式碼如下:

<span class="tag"><<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span> <span class="attribute" style="color:rgb(181,137,0)">id</span>=<span class="value" style="color:rgb(42,161,152)">"main"</span>></span> 
<span class="tag"><<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span> <span class="attribute" style="color:rgb(181,137,0)">id</span>=<span class="value" style="color:rgb(42,161,152)">"mainContainer"</span>></span>main content<span class="tag"></<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span>></span> 
<span class="tag"></<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span>></span> 
<span class="tag"><<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span> <span class="attribute" style="color:rgb(181,137,0)">id</span>=<span class="value" style="color:rgb(42,161,152)">"left"</span>></span> 
<span class="tag"><<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span> <span class="attribute" style="color:rgb(181,137,0)">id</span>=<span class="value" style="color:rgb(42,161,152)">"leftContainer"</span> <span class="attribute" style="color:rgb(181,137,0)">class</span>=<span class="value" style="color:rgb(42,161,152)">"inner"</span>></span>left content<span class="tag"></<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span>></span> 
<span class="tag"></<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span>></span> 
<span class="tag"><<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span> <span class="attribute" style="color:rgb(181,137,0)">id</span>=<span class="value" style="color:rgb(42,161,152)">"right"</span>></span> 
<span class="tag"><<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span> <span class="attribute" style="color:rgb(181,137,0)">id</span>=<span class="value" style="color:rgb(42,161,152)">"rightContainer"</span> <span class="attribute" style="color:rgb(181,137,0)">class</span>=<span class="value" style="color:rgb(42,161,152)">"inner"</span>></span>right<span class="tag"></<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span>></span> 
<span class="tag"></<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span>></span>

簡單的說一下其實作原理，這種方法佈局，主要運用的是負的margin值。首先在p#main中我定了一個100％寬度並進行左浮動，並且主內容是放在其內層p#mainContainer中，並在這個主內容層中需要進行一個margin-left和margin-right設置，而這兩個值是很有講究的，並不是可以隨便設定的，這兩個值需要等於左右兩列的寬度。我們此處是230px。左欄和右欄都使用負的margin值加上左浮動來佈局，左欄是左浮動並加了一個“margin-left:-100%”,這是因為p#left前面有一個p#main，且其寬度為100％，這樣一來在左欄定這個margin-left: -100%;剛好使左邊欄定位到頁面的最左邊；而右欄也進行左浮動，但其定義的“margin-left 」也是負值，並且等於其自身的寬度230px；最後在p#left,p#right中加上一個p.inner是為了更好的控制邊欄與主內容列之間的間距。比如說此例的10px。大家可以看看其效果是不是跟第二種方法一樣。

 上面囉嗦完了常見的佈局方法，接著進我們一起來看另外一種三列佈局中間固定寬度，兩邊自適應寬度。對我來說，這是一種很少碰到的佈局方法，不知道大家有何體會，那麼下面我們一起來看這種佈局方法的實現過程，同樣先來看html程式碼：

代码如下:

<span class="tag"><<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span> <span class="attribute" style="color:rgb(181,137,0)">id</span>=<span class="value" style="color:rgb(42,161,152)">"left"</span>></span> 
<span class="tag"><<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span> <span class="attribute" style="color:rgb(181,137,0)">class</span>=<span class="value" style="color:rgb(42,161,152)">"inner"</span>></span>this is left sidebar content<span class="tag"></<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span>></span> 
<span class="tag"></<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span>></span> 
<span class="tag"><<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span> <span class="attribute" style="color:rgb(181,137,0)">id</span>=<span class="value" style="color:rgb(42,161,152)">"main"</span>></span> 
<span class="tag"><<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span> <span class="attribute" style="color:rgb(181,137,0)">class</span>=<span class="value" style="color:rgb(42,161,152)">"inner"</span>></span>this is main content<span class="tag"></<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span>></span> 
<span class="tag"></<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span>></span> 
<span class="tag"><<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span> <span class="attribute" style="color:rgb(181,137,0)">id</span>=<span class="value" style="color:rgb(42,161,152)">"right"</span>></span> 
<span class="tag"><<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span> <span class="attribute" style="color:rgb(181,137,0)">class</span>=<span class="value" style="color:rgb(42,161,152)">"inner"</span>></span>this is right siderbar content<span class="tag"></<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span>></span> 
<span class="tag"></<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span>></span>

这种方法也是借助于负的margin来实现的，首先我们在中间列定好固定值，因为此值是不会在改变的，接着对其进行左浮动；那么关键地主是在左右边栏设置地方，这种方法是将其都进行50%的宽度设置，并加上中负的左边距，此负的左边距最理想的值是中间栏宽度的一半加上1px，比如说此例中是"540px/2+1"也就是说他们都有一个"margin-left: -271px",这样一来，左右边栏内容无法正常显示，那是因为对他们进行了负的左边距操作，现在只需要在左右边栏的内层p.inner将其拉回来，就ＯＫ了，大家可以看下在的代码： 

代码如下:

<span class="id" style="color:rgb(38,139,210)">#left</span>, <span class="id" style="color:rgb(38,139,210)">#right</span> <span class="rules">{ <span class="rule"><span class="attribute" style="color:rgb(181,137,0)">float</span>:<span class="value"> left;</span></span> <span class="rule"><span class="attribute" style="color:rgb(181,137,0)">margin</span>:<span class="value"> <span class="number" style="color:rgb(42,161,152)">0</span> <span class="number" style="color:rgb(42,161,152)">0</span> <span class="number" style="color:rgb(42,161,152)">0</span> -<span class="number" style="color:rgb(42,161,152)">271</span>px;</span></span> <span class="rule"><span class="attribute" style="color:rgb(181,137,0)">width</span>:<span class="value"> <span class="number" style="color:rgb(42,161,152)">50</span>%;</span></span> <span class="rule">}</span></span> <span class="id" style="color:rgb(38,139,210)">#main</span> <span class="rules">{ <span class="rule"><span class="attribute" style="color:rgb(181,137,0)">width</span>:<span class="value"> <span class="number" style="color:rgb(42,161,152)">540</span>px;</span></span> <span class="rule"><span class="attribute" style="color:rgb(181,137,0)">float</span>:<span class="value"> left;</span></span> <span class="rule"><span class="attribute" style="color:rgb(181,137,0)">background</span>:<span class="value"> green;</span></span> <span class="rule">}</span></span> <span class="class">.inner</span> <span class="rules">{ <span class="rule"><span class="attribute" style="color:rgb(181,137,0)">padding</span>:<span class="value"> <span class="number" style="color:rgb(42,161,152)">20</span>px;</span></span> <span class="rule">}</span></span> <span class="id" style="color:rgb(38,139,210)">#left</span> <span class="class">.inner</span>, <span class="id" style="color:rgb(38,139,210)">#right</span> <span class="class">.inner</span> <span class="rules">{ <span class="rule"><span class="attribute" style="color:rgb(181,137,0)">margin</span>:<span class="value"> <span class="number" style="color:rgb(42,161,152)">0</span> <span class="number" style="color:rgb(42,161,152)">0</span> <span class="number" style="color:rgb(42,161,152)">0</span> <span class="number" style="color:rgb(42,161,152)">271</span>px;</span></span> <span class="rule"><span class="attribute" style="color:rgb(181,137,0)">background</span>:<span class="value"> orange;</span></span> <span class="rule">}</span></span>

具体效果如下：
 
这种方法如果在ie下会存在布局混乱的bug，你可以将p#right和p#left中的width值稍作修改： 

代码如下:

<span class="id" style="color:rgb(38,139,210)">#left</span>, 
<span class="id" style="color:rgb(38,139,210)">#right</span> <span class="rules">{ 
<span class="rule"><span class="attribute" style="color:rgb(181,137,0)">float</span>:<span class="value"> left;</span></span> 
<span class="rule"><span class="attribute" style="color:rgb(181,137,0)">margin</span>:<span class="value"> <span class="number" style="color:rgb(42,161,152)">0</span> <span class="number" style="color:rgb(42,161,152)">0</span> <span class="number" style="color:rgb(42,161,152)">0</span> -<span class="number" style="color:rgb(42,161,152)">271</span>px;</span></span> 
<span class="rule"><span class="attribute" style="color:rgb(181,137,0)">width</span>:<span class="value"> <span class="number" style="color:rgb(42,161,152)">50</span>%;</span></span> 
<span class="rule">*<span class="attribute" style="color:rgb(181,137,0)">width</span>:<span class="value"> <span class="number" style="color:rgb(42,161,152)">49.9</span>%;</span></span> 
<span class="rule">}</span></span>

这样一来，在ie下也就安全了。

实现这种效果的方法可能有很多，希望大家有更好的方法能一起分享一起学习。

2012年09月26日更新——CSS3 Flexbox

前面介绍了三种方法，实现L1F2L3布局效果，也就是第一列和第三列自适应宽度，中间一列固定宽度。今天在给大家推荐一种CSS3实现这种布局的方法，采用CSS3的Flexbox，这种方法 不足之处就是只能在部分浏览器中使用，详细的请看下面代码：

HTML结构

代码如下:

<span class="tag"><<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span> <span class="attribute" style="color:rgb(181,137,0)">class</span>=<span class="value" style="color:rgb(42,161,152)">"grid"</span>></span> 
<span class="tag"><<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span> <span class="attribute" style="color:rgb(181,137,0)">class</span>=<span class="value" style="color:rgb(42,161,152)">"col fluid"</span>></span> 
... 
<span class="tag"></<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span>></span> 
<span class="tag"><<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span> <span class="attribute" style="color:rgb(181,137,0)">class</span>=<span class="value" style="color:rgb(42,161,152)">"col fixed"</span>></span> 
... 
<span class="tag"></<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span>></span> 
<span class="tag"><<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span> <span class="attribute" style="color:rgb(181,137,0)">class</span>=<span class="value" style="color:rgb(42,161,152)">"col fluid"</span>></span> 
... 
<span class="tag"></<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span>></span> 
<span class="tag"></<span class="title" style="margin-left:60px; color:rgb(38,139,210)">p</span>></span>

CSS代码

代码如下:

<span class="class">.grid</span> <span class="rules">{ <span class="rule"><span class="attribute" style="color:rgb(181,137,0)">display</span>:<span class="value"> -webkit-flex;</span></span> <span class="rule"><span class="attribute" style="color:rgb(181,137,0)">display</span>:<span class="value"> -moz-flex;</span></span> <span class="rule"><span class="attribute" style="color:rgb(181,137,0)">display</span>:<span class="value"> -o-flex;</span></span> <span class="rule"><span class="attribute" style="color:rgb(181,137,0)">display</span>:<span class="value"> -ms-flex;</span></span> <span class="rule"><span class="attribute" style="color:rgb(181,137,0)">display</span>:<span class="value"> flex;</span></span> <span class="rule">}</span></span> <span class="class">.col</span> <span class="rules">{ <span class="rule"><span class="attribute" style="color:rgb(181,137,0)">padding</span>:<span class="value"> <span class="number" style="color:rgb(42,161,152)">30</span>px;</span></span> <span class="rule">}</span></span> <span class="class">.fluid</span> <span class="rules">{ <span class="rule"><span class="attribute" style="color:rgb(181,137,0)">flex</span>:<span class="value"> <span class="number" style="color:rgb(42,161,152)">1</span>;</span></span> <span class="rule">}</span></span> <span class="class">.fixed</span> <span class="rules">{ <span class="rule"><span class="attribute" style="color:rgb(181,137,0)">width</span>:<span class="value"> <span class="number" style="color:rgb(42,161,152)">400</span>px;</span></span> <span class="rule">}</span></span>

效果如下面的demo所示：

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