Erhöhen Sie die Anwendungspriorität der angegebenen Stilregel.

Es gibt ein relativ explizites Supportproblem in IE6 und niedrigeren Browsern. !important wird nicht im selben Regelsatz wirksam. Bitte schauen Sie sich den folgenden Code an:

Beispielcode:

div { color: #f00 !important; color: #000; }

Im obigen Code ist die Textfarbe des Div in IE6 und niedrigeren Browsern #000, !important überschreibt nicht die folgenden Regeln; die Textfarbe des Div in anderen Browsern ist #f00
Damit !important in IE6 und niedrigeren Browsern wirksam wird, können Sie den folgenden Code verwenden:

Beispielcode:

div { color: #f00 !important; } div { color: #000; }

Im obigen Code stimmt die Textfarbe von div in IE6 und niedrigeren Browsern mit der anderer Browser überein, beide sind #f00
　Unter IE6 und früheren Browsern wird !important nicht im selben Regelsatz wirksam.
Beispiel:

<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">title</span><span style="color: #0000ff">></span>important的使用<span style="color: #0000ff"></</span><span style="color: #800000">title</span><span style="color: #0000ff">></span>
<span style="color: #008080"> 5</span>     <span style="color: #0000ff"><</span><span style="color: #800000">meta </span><span style="color: #ff0000">name</span><span style="color: #0000ff">="content-type"</span><span style="color: #ff0000"> content</span><span style="color: #0000ff">="text/html; charset=UTF-8"</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">.button </span><span style="background-color: #f5f5f5; color: #000000">{</span>
<span style="color: #008080"> 8</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"> 9</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"> #4CAF50</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">10</span> <span style="background-color: #f5f5f5; color: #ff0000">    border-radius</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff">8px</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">11</span> <span style="background-color: #f5f5f5; color: #ff0000">    font-size</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> 28px</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">12</span> <span style="background-color: #f5f5f5; color: #ff0000">    color</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> #FFFFFF</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">13</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">14</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"> 200px</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">15</span> <span style="background-color: #f5f5f5; color: #ff0000">    text-align</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> center</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">16</span> <span style="background-color: #f5f5f5; color: #ff0000">    transition-duration</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> 1.5s</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">17</span> <span style="background-color: #f5f5f5; color: #ff0000">    overflow</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> hidden</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">18</span> <span style="background-color: #f5f5f5; color: #ff0000">    cursor</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> pointer</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="background-color: #f5f5f5; color: #800000">  .button:hover</span><span style="background-color: #f5f5f5; color: #000000">{</span>
<span style="color: #008080">21</span> <span style="background-color: #f5f5f5; color: #ff0000">    box-shadow</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff">0 4px 8px 0 rgba(0,0,0,0.1),0 6px 20px 0 rgba(0,0,0,0.299)</span><span style="background-color: #f5f5f5; color: #000000">;</span>  
<span style="color: #008080">22</span>   <span style="background-color: #f5f5f5; color: #000000">}</span>
<span style="color: #008080">23</span> 
<span style="color: #008080">24</span> <span style="background-color: #f5f5f5; color: #800000">  .button:after </span><span style="background-color: #f5f5f5; color: #000000">{</span>
<span style="color: #008080">25</span> <span style="background-color: #f5f5f5; color: #ff0000">    content</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> ""</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">26</span> <span style="background-color: #f5f5f5; color: #ff0000">    background</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> #90EE90</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">27</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"> block</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">28</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">29</span> <span style="background-color: #f5f5f5; color: #ff0000">    padding-top</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> 300%</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">30</span> <span style="background-color: #f5f5f5; color: #ff0000">    padding-left</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> 350%</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">31</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"> -20px!important</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">32</span> <span style="background-color: #f5f5f5; color: #ff0000">    margin-top</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> -120%</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">33</span> <span style="background-color: #f5f5f5; color: #ff0000">    opacity</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">34</span> <span style="background-color: #f5f5f5; color: #ff0000">    transition</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff">1s</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">35</span> <span style="background-color: #f5f5f5; color: #000000">}</span>
<span style="color: #008080">36</span> 
<span style="color: #008080">37</span> <span style="background-color: #f5f5f5; color: #800000">.button:active:after </span><span style="background-color: #f5f5f5; color: #000000">{</span>
<span style="color: #008080">38</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"> 0</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">39</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"> 0</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">40</span> <span style="background-color: #f5f5f5; color: #ff0000">    opacity</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> 1</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">41</span> <span style="background-color: #f5f5f5; color: #ff0000">    transition</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff">0s</span><span style="background-color: #f5f5f5; color: #000000">;</span>
<span style="color: #008080">42</span> <span style="background-color: #f5f5f5; color: #000000">}</span>
<span style="color: #008080">43</span> <span style="color: #0000ff"></</span><span style="color: #800000">style</span><span style="color: #0000ff">></span>
<span style="color: #008080">44</span> <span style="color: #0000ff"></</span><span style="color: #800000">head</span><span style="color: #0000ff">></span>
<span style="color: #008080">45</span> <span style="color: #0000ff"><</span><span style="color: #800000">body</span><span style="color: #0000ff">></span>
<span style="color: #008080">46</span> 
<span style="color: #008080">47</span> <span style="color: #0000ff"><</span><span style="color: #800000">button </span><span style="color: #ff0000">class</span><span style="color: #0000ff">="button"</span><span style="color: #0000ff">></span>Click Me<span style="color: #0000ff"></</span><span style="color: #800000">button</span><span style="color: #0000ff">></span>
<span style="color: #008080">48</span> <p>第31行的margin-left设置了!important，因此后面的第39行是不能更改margin-left的值。
<span style="color: #008080">50</span> <span style="color: #0000ff"></</span><span style="color: #800000">body</span><span style="color: #0000ff">></span>
<span style="color: #008080">51</span> <span style="color: #0000ff"></</span><span style="color: #800000">html</span><span style="color: #0000ff">></span>
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Referenzartikel:
http://www.runoob.com/css3/css3-buttons.html
http://www.css88.com/book/css/rules/!important.htm
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