CSS position:absolute浅析

<span style="color: #008080;"> 1</span> <span style="color: #0000ff;"><!</span><span style="color: #ff00ff;">DOCTYPE html</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 2</span> <span style="color: #0000ff;"><</span><span style="color: #800000;">html</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 3</span>     <span style="color: #0000ff;"><</span><span style="color: #800000;">head</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 4</span>         <span style="color: #0000ff;"><</span><span style="color: #800000;">meta </span><span style="color: #ff0000;">charset</span><span style="color: #0000ff;">="utf-8"</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 5</span>         <span style="color: #0000ff;"><</span><span style="color: #800000;">title</span><span style="color: #0000ff;">></span>绝对定位的特征<span style="color: #0000ff;"></</span><span style="color: #800000;">title</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 6</span>         <span style="color: #0000ff;"><</span><span style="color: #800000;">style</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 7</span> <span style="background-color: #f5f5f5; color: #800000;">            .box1,.box2,.box3 </span><span style="background-color: #f5f5f5; color: #000000;">{</span>
<span style="color: #008080;"> 8</span> <span style="background-color: #f5f5f5; color: #ff0000;">                background-color</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;"> orange</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;"> 9</span> <span style="background-color: #f5f5f5; color: #ff0000;">                margin-bottom</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;"> 30px</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">10</span>             <span style="background-color: #f5f5f5; color: #000000;">}</span>
<span style="color: #008080;">11</span> 
<span style="color: #008080;">12</span> <span style="background-color: #f5f5f5; color: #800000;">            .absolute </span><span style="background-color: #f5f5f5; color: #000000;">{</span>
<span style="color: #008080;">13</span> <span style="background-color: #f5f5f5; color: #ff0000;">                position</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;"> absolute</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">14</span>             <span style="background-color: #f5f5f5; color: #000000;">}</span>
<span style="color: #008080;">15</span> 
<span style="color: #008080;">16</span> <span style="background-color: #f5f5f5; color: #800000;">            .wraper </span><span style="background-color: #f5f5f5; color: #000000;">{</span>
<span style="color: #008080;">17</span> <span style="background-color: #f5f5f5; color: #ff0000;">                display</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;">inline-block</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">18</span> <span style="background-color: #f5f5f5; color: #ff0000;">                margin-left</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;"> 300px</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">19</span>             <span style="background-color: #f5f5f5; color: #000000;">}</span>
<span style="color: #008080;">20</span> 
<span style="color: #008080;">21</span> <span style="background-color: #f5f5f5; color: #800000;">            .float </span><span style="background-color: #f5f5f5; color: #000000;">{</span>
<span style="color: #008080;">22</span> <span style="background-color: #f5f5f5; color: #ff0000;">                float</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;"> left</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">23</span>             <span style="background-color: #f5f5f5; color: #000000;">}</span>
<span style="color: #008080;">24</span>             
<span style="color: #008080;">25</span> <span style="background-color: #f5f5f5; color: #800000;">            .box3 </span><span style="background-color: #f5f5f5; color: #000000;">{</span>
<span style="color: #008080;">26</span> <span style="background-color: #f5f5f5; color: #ff0000;">                position</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;"> absolute</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">27</span>             <span style="background-color: #f5f5f5; color: #000000;">}</span>
<span style="color: #008080;">28</span>         <span style="color: #0000ff;"></</span><span style="color: #800000;">style</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">29</span>     <span style="color: #0000ff;"></</span><span style="color: #800000;">head</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">30</span>     <span style="color: #0000ff;"><</span><span style="color: #800000;">body</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">31</span>         <span style="color: #0000ff;"><</span><span style="color: #800000;">div </span><span style="color: #ff0000;">class</span><span style="color: #0000ff;">="box1"</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">32</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">img </span><span style="color: #ff0000;">src</span><span style="color: #0000ff;">="http://a.hiphotos.baidu.com/zhidao/pic/item/72f082025aafa40fa38bfc55a964034f79f019ec.jpg"</span><span style="color: #ff0000;"> alt</span><span style="color: #0000ff;">="A picture"</span><span style="color: #ff0000;"> style</span><span style="color: #0000ff;">="width:175px;height:100px"</span> <span style="color: #0000ff;">/></span>
<span style="color: #008080;">33</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">img </span><span style="color: #ff0000;">src</span><span style="color: #0000ff;">="http://pic1.win4000.com/wallpaper/c/537b28b60619b.jpg"</span><span style="color: #ff0000;"> alt</span><span style="color: #0000ff;">="A picture"</span><span style="color: #ff0000;"> style</span><span style="color: #0000ff;">="width:240px;height:180px"</span> <span style="color: #0000ff;">/></span>
<span style="color: #008080;">34</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>这是普通流中的两幅图像。<span style="color: #0000ff;"></</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">35</span>         <span style="color: #0000ff;"></</span><span style="color: #800000;">div</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">36</span>         <span style="color: #0000ff;"><</span><span style="color: #800000;">div </span><span style="color: #ff0000;">class</span><span style="color: #0000ff;">="box2"</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">37</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">img </span><span style="color: #ff0000;">class</span><span style="color: #0000ff;">="absolute"</span><span style="color: #ff0000;"> src</span><span style="color: #0000ff;">="http://a.hiphotos.baidu.com/zhidao/pic/item/72f082025aafa40fa38bfc55a964034f79f019ec.jpg"</span><span style="color: #ff0000;"> alt</span><span style="color: #0000ff;">="A picture"</span><span style="color: #ff0000;"> style</span><span style="color: #0000ff;">="width:175px;height:100px"</span> <span style="color: #0000ff;">/></span>
<span style="color: #008080;">38</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">img </span><span style="color: #ff0000;">src</span><span style="color: #0000ff;">="http://pic1.win4000.com/wallpaper/c/537b28b60619b.jpg"</span><span style="color: #ff0000;"> alt</span><span style="color: #0000ff;">="A picture"</span><span style="color: #ff0000;"> style</span><span style="color: #0000ff;">="width:240px;height:180px"</span> <span style="color: #0000ff;">/></span>
<span style="color: #008080;">39</span> 
<span style="color: #008080;">40</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">div </span><span style="color: #ff0000;">class</span><span style="color: #0000ff;">="wraper"</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">41</span>                 <span style="color: #0000ff;"><</span><span style="color: #800000;">img </span><span style="color: #ff0000;">class</span><span style="color: #0000ff;">="float"</span><span style="color: #ff0000;"> src</span><span style="color: #0000ff;">="http://a.hiphotos.baidu.com/zhidao/pic/item/72f082025aafa40fa38bfc55a964034f79f019ec.jpg"</span><span style="color: #ff0000;"> alt</span><span style="color: #0000ff;">="A picture"</span><span style="color: #ff0000;"> style</span><span style="color: #0000ff;">="width:175px;height:100px"</span> <span style="color: #0000ff;">/></span>
<span style="color: #008080;">42</span>                 <span style="color: #0000ff;"><</span><span style="color: #800000;">img </span><span style="color: #ff0000;">src</span><span style="color: #0000ff;">="http://pic1.win4000.com/wallpaper/c/537b28b60619b.jpg"</span><span style="color: #ff0000;"> alt</span><span style="color: #0000ff;">="A picture"</span><span style="color: #ff0000;"> style</span><span style="color: #0000ff;">="width:240px;height:180px"</span> <span style="color: #0000ff;">/></span>
<span style="color: #008080;">43</span>             <span style="color: #0000ff;"></</span><span style="color: #800000;">div</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">44</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>左图，将第一幅图像绝对定位，其完全脱离文档流，并且覆盖在第二幅图像之上；由此看出，绝对定位的破坏性不仅让元素没有了高度，甚至没有了宽度。<span style="color: #0000ff;"></</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">45</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>右图，将第一幅图像左浮动，其虽然脱离了文档流，但是并没有覆盖在其他元素之上；浮动的破坏性仅仅破坏了元素的高度，而保留了元素的宽度。<span style="color: #0000ff;"></</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">46</span>         <span style="color: #0000ff;"></</span><span style="color: #800000;">div</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">47</span>         <span style="color: #0000ff;"><</span><span style="color: #800000;">div </span><span style="color: #ff0000;">class</span><span style="color: #0000ff;">="box3"</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">48</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">img </span><span style="color: #ff0000;">src</span><span style="color: #0000ff;">="http://a.hiphotos.baidu.com/zhidao/pic/item/72f082025aafa40fa38bfc55a964034f79f019ec.jpg"</span><span style="color: #ff0000;"> alt</span><span style="color: #0000ff;">="A picture"</span><span style="color: #ff0000;"> style</span><span style="color: #0000ff;">="width:175px;height:100px"</span> <span style="color: #0000ff;">/></span>
<span style="color: #008080;">49</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">img </span><span style="color: #ff0000;">src</span><span style="color: #0000ff;">="http://pic1.win4000.com/wallpaper/c/537b28b60619b.jpg"</span><span style="color: #ff0000;"> alt</span><span style="color: #0000ff;">="A picture"</span><span style="color: #ff0000;"> style</span><span style="color: #0000ff;">="width:240px;height:180px"</span> <span style="color: #0000ff;">/></span>
<span style="color: #008080;">50</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>将容器绝对定位，体现其包裹性。<span style="color: #0000ff;"></</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">51</span>         <span style="color: #0000ff;"></</span><span style="color: #800000;">div</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">52</span>     <span style="color: #0000ff;"></</span><span style="color: #800000;">body</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">53</span> <span style="color: #0000ff;"></</span><span style="color: #800000;">html</span><span style="color: #0000ff;">></span>

<span style="color: #008080;"> 1</span> <span style="color: #0000ff;"><!</span><span style="color: #ff00ff;">DOCTYPE html</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 2</span> <span style="color: #0000ff;"><</span><span style="color: #800000;">html</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 3</span>     <span style="color: #0000ff;"><</span><span style="color: #800000;">head</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 4</span>         <span style="color: #0000ff;"><</span><span style="color: #800000;">meta </span><span style="color: #ff0000;">charset</span><span style="color: #0000ff;">="utf-8"</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 5</span>         <span style="color: #0000ff;"><</span><span style="color: #800000;">title</span><span style="color: #0000ff;">></span>绝对定位的一般规则<span style="color: #0000ff;"></</span><span style="color: #800000;">title</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 6</span>         <span style="color: #0000ff;"><</span><span style="color: #800000;">style</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 7</span> <span style="background-color: #f5f5f5; color: #800000;">            body </span><span style="background-color: #f5f5f5; color: #000000;">{</span>
<span style="color: #008080;"> 8</span> <span style="background-color: #f5f5f5; color: #ff0000;">                background-color</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;"> #ccc</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;"> 9</span>             <span style="background-color: #f5f5f5; color: #000000;">}</span>
<span style="color: #008080;">10</span> <span style="background-color: #f5f5f5; color: #800000;">            .container </span><span style="background-color: #f5f5f5; color: #000000;">{</span>
<span style="color: #008080;">11</span> <span style="background-color: #f5f5f5; color: #ff0000;">                width</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;">500px</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">12</span> <span style="background-color: #f5f5f5; color: #ff0000;">                background-color</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;"> orange</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">13</span> <span style="background-color: #f5f5f5; color: #ff0000;">                margin</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;">20px auto 50px auto</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">14</span> <span style="background-color: #f5f5f5; color: #ff0000;">                padding</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;">20px</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">15</span> <span style="background-color: #f5f5f5; color: #ff0000;">                border</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;">2px solid red</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">16</span>             <span style="background-color: #f5f5f5; color: #000000;">}</span>
<span style="color: #008080;">17</span> 
<span style="color: #008080;">18</span> <span style="background-color: #f5f5f5; color: #800000;">            .box2 img,.box3 img,
</span><span style="color: #008080;">19</span> <span style="background-color: #f5f5f5; color: #800000;">            .box4 img,.box5 img </span><span style="background-color: #f5f5f5; color: #000000;">{</span>
<span style="color: #008080;">20</span> <span style="background-color: #f5f5f5; color: #ff0000;">                position</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;"> absolute</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">21</span>             <span style="background-color: #f5f5f5; color: #000000;">}</span>
<span style="color: #008080;">22</span> 
<span style="color: #008080;">23</span> <span style="background-color: #f5f5f5; color: #800000;">            .box3 img,.box4 img </span><span style="background-color: #f5f5f5; color: #000000;">{</span>
<span style="color: #008080;">24</span> <span style="background-color: #f5f5f5; color: #ff0000;">                left</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;">0</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">25</span> <span style="background-color: #f5f5f5; color: #ff0000;">                bottom</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;">0</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">26</span>             <span style="background-color: #f5f5f5; color: #000000;">}</span>
<span style="color: #008080;">27</span> 
<span style="color: #008080;">28</span> <span style="background-color: #f5f5f5; color: #800000;">            .box5 img </span><span style="background-color: #f5f5f5; color: #000000;">{</span>
<span style="color: #008080;">29</span> <span style="background-color: #f5f5f5; color: #ff0000;">                left</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;"> -30px</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">30</span> <span style="background-color: #f5f5f5; color: #ff0000;">                bottom</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;"> -50px</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">31</span>             <span style="background-color: #f5f5f5; color: #000000;">}</span>
<span style="color: #008080;">32</span> 
<span style="color: #008080;">33</span> <span style="background-color: #f5f5f5; color: #800000;">            .block </span><span style="background-color: #f5f5f5; color: #000000;">{</span>
<span style="color: #008080;">34</span> <span style="background-color: #f5f5f5; color: #ff0000;">                position </span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;">relative</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">35</span> <span style="background-color: #f5f5f5; color: #ff0000;">                height</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;"> 200px</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">36</span>             <span style="background-color: #f5f5f5; color: #000000;">}</span>
<span style="color: #008080;">37</span>         <span style="color: #0000ff;"></</span><span style="color: #800000;">style</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">38</span>     <span style="color: #0000ff;"></</span><span style="color: #800000;">head</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">39</span>     <span style="color: #0000ff;"><</span><span style="color: #800000;">body</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">40</span>         <span style="color: #0000ff;"><</span><span style="color: #800000;">div </span><span style="color: #ff0000;">class</span><span style="color: #0000ff;">="container"</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">41</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">div </span><span style="color: #ff0000;">class</span><span style="color: #0000ff;">="box1"</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">42</span>                 <span style="color: #0000ff;"><</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>元素绝对定位时，会完全脱离文档流，并相对于其包含块定位。绝对定位的包含块，是其最近的已定位的祖先元素。<span style="color: #0000ff;"></</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">43</span>                 <span style="color: #0000ff;"><</span><span style="color: #800000;">img </span><span style="color: #ff0000;">src</span><span style="color: #0000ff;">="http://a.hiphotos.baidu.com/zhidao/pic/item/72f082025aafa40fa38bfc55a964034f79f019ec.jpg"</span><span style="color: #ff0000;"> alt</span><span style="color: #0000ff;">="A picture"</span><span style="color: #ff0000;"> style</span><span style="color: #0000ff;">="width:175px;height:100px"</span> <span style="color: #0000ff;">/></span>
<span style="color: #008080;">44</span>                 <span style="color: #0000ff;"><</span><span style="color: #800000;">ul</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">45</span>                     <span style="color: #0000ff;"><</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>如果这个祖先元素是块级元素，包含块则为该祖先元素的内边距边界，即边框。<span style="color: #0000ff;"></</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">46</span>                     <span style="color: #0000ff;"><</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>如果这个祖先元素是行内元素，包含块则为该祖先元素的内容边界，即内容区。<span style="color: #0000ff;"></</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">47</span>                     <span style="color: #0000ff;"><</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>如果没有已定位的祖先元素，元素的包含块定义为初始包含块（一个视窗大小的矩形）。<span style="color: #0000ff;"></</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>      
<span style="color: #008080;">48</span>                 <span style="color: #0000ff;"></</span><span style="color: #800000;">ul</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">49</span>             <span style="color: #0000ff;"></</span><span style="color: #800000;">div</span><span style="color: #0000ff;">></span><span style="color: #008000;"><!--</span><span style="color: #008000;">关闭box1</span><span style="color: #008000;">--></span>
<span style="color: #008080;">50</span>         <span style="color: #0000ff;"></</span><span style="color: #800000;">div</span><span style="color: #0000ff;">></span><span style="color: #008000;"><!--</span><span style="color: #008000;">关闭container</span><span style="color: #008000;">--></span>
<span style="color: #008080;">51</span>         <span style="color: #0000ff;"><</span><span style="color: #800000;">div </span><span style="color: #ff0000;">class</span><span style="color: #0000ff;">="container"</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">52</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">div </span><span style="color: #ff0000;">class</span><span style="color: #0000ff;">="box2"</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">53</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>不管有没有已经定位的祖先元素，只要没有偏移量，绝对定位之后，原地不动，脱离文档流。<span style="color: #0000ff;"></</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">54</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>下面这个已经绝对定位的图像原地没动，但是已经脱离了文档流。<span style="color: #0000ff;"></</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">55</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">img </span><span style="color: #ff0000;">src</span><span style="color: #0000ff;">="http://a.hiphotos.baidu.com/zhidao/pic/item/72f082025aafa40fa38bfc55a964034f79f019ec.jpg"</span><span style="color: #ff0000;"> alt</span><span style="color: #0000ff;">="A picture"</span><span style="color: #ff0000;"> style</span><span style="color: #0000ff;">="width:175px;height:100px"</span> <span style="color: #0000ff;">/></span>
<span style="color: #008080;">56</span>             <span style="color: #0000ff;"></</span><span style="color: #800000;">div</span><span style="color: #0000ff;">></span><span style="color: #008000;"><!--</span><span style="color: #008000;">关闭box2</span><span style="color: #008000;">--></span>
<span style="color: #008080;">57</span>         <span style="color: #0000ff;"></</span><span style="color: #800000;">div</span><span style="color: #0000ff;">></span><span style="color: #008000;"><!--</span><span style="color: #008000;">关闭container</span><span style="color: #008000;">--></span>
<span style="color: #008080;">58</span>         <span style="color: #0000ff;"><</span><span style="color: #800000;">div </span><span style="color: #ff0000;">class</span><span style="color: #0000ff;">="container"</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">59</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">div </span><span style="color: #ff0000;">class</span><span style="color: #0000ff;">="box3"</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">60</span>                 <span style="color: #0000ff;"><</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>没有已经定位的祖先元素，有偏移量，绝对定位之后，以初始包含块（一个视窗大小的矩形）为基准进行偏移。<span style="color: #0000ff;"></</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">61</span>                 <span style="color: #0000ff;"><</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>当偏移量为left:0; buttom:0时，图像水平偏移到了初始包含块左下角（打开网页最开始的那一个视窗的左下角）。<span style="color: #0000ff;"></</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">62</span>                 <span style="color: #0000ff;"><</span><span style="color: #800000;">img </span><span style="color: #ff0000;">src</span><span style="color: #0000ff;">="http://a.hiphotos.baidu.com/zhidao/pic/item/72f082025aafa40fa38bfc55a964034f79f019ec.jpg"</span><span style="color: #ff0000;"> alt</span><span style="color: #0000ff;">="A picture"</span><span style="color: #ff0000;"> style</span><span style="color: #0000ff;">="width:175px;height:100px"</span> <span style="color: #0000ff;">/></span>
<span style="color: #008080;">63</span>             <span style="color: #0000ff;"></</span><span style="color: #800000;">div</span><span style="color: #0000ff;">></span><span style="color: #008000;"><!--</span><span style="color: #008000;">关闭box3</span><span style="color: #008000;">--></span>
<span style="color: #008080;">64</span>         <span style="color: #0000ff;"></</span><span style="color: #800000;">div</span><span style="color: #0000ff;">></span><span style="color: #008000;"><!--</span><span style="color: #008000;">关闭container</span><span style="color: #008000;">--></span>
<span style="color: #008080;">65</span>         <span style="color: #0000ff;"><</span><span style="color: #800000;">div </span><span style="color: #ff0000;">class</span><span style="color: #0000ff;">="container block"</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">66</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">div </span><span style="color: #ff0000;">class</span><span style="color: #0000ff;">="box4"</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">67</span>                 <span style="color: #0000ff;"><</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>有已经定位的祖先元素，有偏移量，绝对定位之后，以已经定位的祖先元素为基准进行偏移。<span style="color: #0000ff;"></</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">68</span>                 <span style="color: #0000ff;"><</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>此处已经定位的祖先元素为这个图像的容器div元素，偏移量为left:0; bottom:0时，图像到了这个容器的左下角（以边框为界）。<span style="color: #0000ff;"></</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">69</span>                 <span style="color: #0000ff;"><</span><span style="color: #800000;">img </span><span style="color: #ff0000;">src</span><span style="color: #0000ff;">="http://a.hiphotos.baidu.com/zhidao/pic/item/72f082025aafa40fa38bfc55a964034f79f019ec.jpg"</span><span style="color: #ff0000;"> alt</span><span style="color: #0000ff;">="A picture"</span><span style="color: #ff0000;"> style</span><span style="color: #0000ff;">="width:175px;height:100px"</span> <span style="color: #0000ff;">/></span>
<span style="color: #008080;">70</span>             <span style="color: #0000ff;"></</span><span style="color: #800000;">div</span><span style="color: #0000ff;">></span><span style="color: #008000;"><!--</span><span style="color: #008000;">关闭box4</span><span style="color: #008000;">--></span>
<span style="color: #008080;">71</span>         <span style="color: #0000ff;"></</span><span style="color: #800000;">div</span><span style="color: #0000ff;">></span><span style="color: #008000;"><!--</span><span style="color: #008000;">关闭container</span><span style="color: #008000;">--></span>
<span style="color: #008080;">72</span>         <span style="color: #0000ff;"><</span><span style="color: #800000;">div </span><span style="color: #ff0000;">class</span><span style="color: #0000ff;">="container block"</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">73</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">div </span><span style="color: #ff0000;">class</span><span style="color: #0000ff;">="box5"</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">74</span>                 <span style="color: #0000ff;"><</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>有已经定位的祖先元素，有偏移量，绝对定位之后，以已经定位的祖先元素为基准进行偏移。<span style="color: #0000ff;"></</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">75</span>                 <span style="color: #0000ff;"><</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>此处已经定位的祖先元素为这个图像的容器div元素，偏移量为left:-30px; bottom:-50px时，图像到了这个容器之外（以边框为界）。<span style="color: #0000ff;"></</span><span style="color: #800000;">p</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">76</span>                 <span style="color: #0000ff;"><</span><span style="color: #800000;">img </span><span style="color: #ff0000;">src</span><span style="color: #0000ff;">="http://a.hiphotos.baidu.com/zhidao/pic/item/72f082025aafa40fa38bfc55a964034f79f019ec.jpg"</span><span style="color: #ff0000;"> alt</span><span style="color: #0000ff;">="A picture"</span><span style="color: #ff0000;"> style</span><span style="color: #0000ff;">="width:175px;height:100px"</span> <span style="color: #0000ff;">/></span>
<span style="color: #008080;">77</span>             <span style="color: #0000ff;"></</span><span style="color: #800000;">div</span><span style="color: #0000ff;">></span><span style="color: #008000;"><!--</span><span style="color: #008000;">关闭box5</span><span style="color: #008000;">--></span>
<span style="color: #008080;">78</span>         <span style="color: #0000ff;"></</span><span style="color: #800000;">div</span><span style="color: #0000ff;">></span><span style="color: #008000;"><!--</span><span style="color: #008000;">关闭container</span><span style="color: #008000;">--></span>
<span style="color: #008080;">79</span>     <span style="color: #0000ff;"></</span><span style="color: #800000;">body</span><span style="color: #0000ff;">></span>    
<span style="color: #008080;">80</span> <span style="color: #0000ff;"></</span><span style="color: #800000;">html</span><span style="color: #0000ff;">></span>

<span style="color: #008080;"> 1</span> <span style="color: #0000ff;"><!</span><span style="color: #ff00ff;">DOCTYPE html</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 2</span> <span style="color: #0000ff;"><</span><span style="color: #800000;">html</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 3</span>     <span style="color: #0000ff;"><</span><span style="color: #800000;">head</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 4</span>         <span style="color: #0000ff;"><</span><span style="color: #800000;">meta </span><span style="color: #ff0000;">charset</span><span style="color: #0000ff;">="utf-8"</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 5</span>         <span style="color: #0000ff;"><</span><span style="color: #800000;">title</span><span style="color: #0000ff;">></span>用margin调整绝对定位元素的位置<span style="color: #0000ff;"></</span><span style="color: #800000;">title</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 6</span>         <span style="color: #0000ff;"><</span><span style="color: #800000;">style</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 7</span> <span style="background-color: #f5f5f5; color: #800000;">            .box1,.box2,.box3 </span><span style="background-color: #f5f5f5; color: #000000;">{</span>
<span style="color: #008080;"> 8</span> <span style="background-color: #f5f5f5; color: #ff0000;">                display</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;"> inline-block</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;"> 9</span> <span style="background-color: #f5f5f5; color: #ff0000;">                margin-right</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;"> 150px</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">10</span> <span style="background-color: #f5f5f5; color: #ff0000;">                border</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;">1px solid blue</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">11</span>             <span style="background-color: #f5f5f5; color: #000000;">}</span>
<span style="color: #008080;">12</span>     
<span style="color: #008080;">13</span> <span style="background-color: #f5f5f5; color: #800000;">            span </span><span style="background-color: #f5f5f5; color: #000000;">{</span>
<span style="color: #008080;">14</span> <span style="background-color: #f5f5f5; color: #ff0000;">                background-color</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;"> red</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">15</span>             <span style="background-color: #f5f5f5; color: #000000;">}</span>
<span style="color: #008080;">16</span>     
<span style="color: #008080;">17</span> <span style="background-color: #f5f5f5; color: #800000;">            .box2 span,.box3 span </span><span style="background-color: #f5f5f5; color: #000000;">{</span>
<span style="color: #008080;">18</span> <span style="background-color: #f5f5f5; color: #ff0000;">                position</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;"> absolute</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">19</span>             <span style="background-color: #f5f5f5; color: #000000;">}</span>
<span style="color: #008080;">20</span>     
<span style="color: #008080;">21</span> <span style="background-color: #f5f5f5; color: #800000;">            .meng </span><span style="background-color: #f5f5f5; color: #000000;">{</span>
<span style="color: #008080;">22</span> <span style="background-color: #f5f5f5; color: #ff0000;">                margin-left</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;"> -3em</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">23</span>             <span style="background-color: #f5f5f5; color: #000000;">}</span>
<span style="color: #008080;">24</span>     
<span style="color: #008080;">25</span> <span style="background-color: #f5f5f5; color: #800000;">            .box4 </span><span style="background-color: #f5f5f5; color: #000000;">{</span>
<span style="color: #008080;">26</span> <span style="background-color: #f5f5f5; color: #ff0000;">                border</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;">1px solid red</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">27</span> <span style="background-color: #f5f5f5; color: #ff0000;">                width</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;"> 500px</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">28</span> <span style="background-color: #f5f5f5; color: #ff0000;">                margin</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;"> 50px auto 0 auto</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">29</span> <span style="background-color: #f5f5f5; color: #ff0000;">                padding</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;">20px</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">30</span>             <span style="background-color: #f5f5f5; color: #000000;">}</span>
<span style="color: #008080;">31</span> 
<span style="color: #008080;">32</span> <span style="background-color: #f5f5f5; color: #800000;">            li </span><span style="background-color: #f5f5f5; color: #000000;">{</span>
<span style="color: #008080;">33</span> <span style="background-color: #f5f5f5; color: #ff0000;">                margin-bottom</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;"> 20px</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="color: #008080;">34</span>             <span style="background-color: #f5f5f5; color: #000000;">}</span>
<span style="color: #008080;">35</span>         <span style="color: #0000ff;"></</span><span style="color: #800000;">style</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">36</span>     <span style="color: #0000ff;"></</span><span style="color: #800000;">head</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">37</span>     <span style="color: #0000ff;"><</span><span style="color: #800000;">body</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">38</span>         <span style="color: #0000ff;"><</span><span style="color: #800000;">div </span><span style="color: #ff0000;">class</span><span style="color: #0000ff;">="box1"</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">39</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">span</span><span style="color: #0000ff;">></span>卡哇伊<span style="color: #0000ff;"></</span><span style="color: #800000;">span</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">40</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">img </span><span style="color: #ff0000;">src</span><span style="color: #0000ff;">="http://imgsrc.baidu.com/forum/w%3D580/sign=0c101fe665380cd7e61ea2e59145ad14/f9a3492762d0f7032de1758a08fa513d2797c542.jpg"</span><span style="color: #ff0000;"> style</span><span style="color: #0000ff;">="width:200px;height:300px"</span> <span style="color: #0000ff;">/></span>
<span style="color: #008080;">41</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">span</span><span style="color: #0000ff;">></span>萌萌哒<span style="color: #0000ff;"></</span><span style="color: #800000;">span</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">42</span>         <span style="color: #0000ff;"></</span><span style="color: #800000;">div</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">43</span>         <span style="color: #0000ff;"><</span><span style="color: #800000;">div </span><span style="color: #ff0000;">class</span><span style="color: #0000ff;">="box2"</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">44</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">span</span><span style="color: #0000ff;">></span>卡哇伊<span style="color: #0000ff;"></</span><span style="color: #800000;">span</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">45</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">img </span><span style="color: #ff0000;">src</span><span style="color: #0000ff;">="http://imgsrc.baidu.com/forum/w%3D580/sign=0c101fe665380cd7e61ea2e59145ad14/f9a3492762d0f7032de1758a08fa513d2797c542.jpg"</span><span style="color: #ff0000;"> style</span><span style="color: #0000ff;">="width:200px;height:300px"</span> <span style="color: #0000ff;">/></span>
<span style="color: #008080;">46</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">span</span><span style="color: #0000ff;">></span>萌萌哒<span style="color: #0000ff;"></</span><span style="color: #800000;">span</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">47</span>             <span style="color: #0000ff;"></</span><span style="color: #800000;">div</span><span style="color: #0000ff;">></span>    
<span style="color: #008080;">48</span>         <span style="color: #0000ff;"><</span><span style="color: #800000;">div </span><span style="color: #ff0000;">class</span><span style="color: #0000ff;">="box3"</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">49</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">span</span><span style="color: #0000ff;">></span>卡哇伊<span style="color: #0000ff;"></</span><span style="color: #800000;">span</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">50</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">img </span><span style="color: #ff0000;">src</span><span style="color: #0000ff;">="http://imgsrc.baidu.com/forum/w%3D580/sign=0c101fe665380cd7e61ea2e59145ad14/f9a3492762d0f7032de1758a08fa513d2797c542.jpg"</span><span style="color: #ff0000;"> style</span><span style="color: #0000ff;">="width:200px;height:300px"</span> <span style="color: #0000ff;">/></span>
<span style="color: #008080;">51</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">span </span><span style="color: #ff0000;">class</span><span style="color: #0000ff;">="meng"</span><span style="color: #0000ff;">></span>萌萌哒<span style="color: #0000ff;"></</span><span style="color: #800000;">span</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">52</span>         <span style="color: #0000ff;"></</span><span style="color: #800000;">div</span><span style="color: #0000ff;">></span>    
<span style="color: #008080;">53</span>         <span style="color: #0000ff;"><</span><span style="color: #800000;">div </span><span style="color: #ff0000;">class</span><span style="color: #0000ff;">="box4"</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">54</span>             <span style="color: #0000ff;"><</span><span style="color: #800000;">ol</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">55</span>                 <span style="color: #0000ff;"><</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>第一幅图，最开始的样子。<span style="color: #0000ff;"></</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">56</span>                 <span style="color: #0000ff;"><</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>第二幅图，两个标签绝对定位，但是不指定任何偏移量。<span style="color: #0000ff;"></</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">57</span>                 <span style="color: #0000ff;"><</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>第三幅图，用margin负值调整&ldquo;萌萌哒&rdquo;的位置，完成。<span style="color: #0000ff;"></</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">58</span>             <span style="color: #0000ff;"></</span><span style="color: #800000;">ol</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">59</span>         <span style="color: #0000ff;"></</span><span style="color: #800000;">div</span><span style="color: #0000ff;">></span>        
<span style="color: #008080;">60</span>     <span style="color: #0000ff;"></</span><span style="color: #800000;">body</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">61</span> <span style="color: #0000ff;"></</span><span style="color: #800000;">html</span><span style="color: #0000ff;">></span>