为了说明css选择器优先级(权重),首先我们来看以下两个实例代码:
<code class="language-html"><style type="text/css"> div.ui_infor p {font-size: 16px;} .ui_infor p {font-size: 14px;} </style> </code>
<code class="language-html"><div class="ui_infor"> <p>test of css</p> </div> </code>
以上例子,最终的显示效果是 font-size: 16px,并不是后面的font-size: 14px;
这种组合的选择器有快速方法判断:
0,0,0,0
第一位数值是代表写在标签上的样式,如
<code class="language-html"><p style="font-size: 14px;"></p> </code>
第二位数值代表的是id选择器,如 #demo {}
第三位数值是代表: 类名( .demo {} )或 伪类(:hover)或 属性选择器[rel=”xx”]
第四位数值是代表:标签选择器 p {}
现在用第一个例子来实践下:
<code class="language-css">div.ui_infor p {font-size: 16px;} </code>
它的权重是:0,0,1,2
<code class="language-css">.ui_infor p {font-size: 14px;} </code>
它的权重是:0,0,1,1
结果:0,0,1,2 > 0,0,1,1,所以显示font-size: 16px;
补充:! important权重是最高的,所以就不用判断了,但在IE-6浏览器中点BUG。
例子:
<code class="language-css">p {font-size: 18px !important;font-size: 12px;} </code>
在IE-6浏览器里面,是显示font-size: 12px,网上有些资料说IE-6不支持!important,其实是不对的。
我们在看看例子:
<code class="language-css">p {font-size: 18px !important;} p {font-size: 12px;} </code>
在IE-6中是显示font-size: 18px,这就说明了IE-6是支持!important,只是表现有点怪异,怪异的地方就是:写在同行的同名样式中 !important的属性被后面的覆盖,
就如 p {font-size: 18px !important;font-size: 12px;} 这个例子,font-size: 12px覆盖了font-size: 18px !important。
利用这个怪异,就可以在IE-6中,不使用CSS_hack,实现“min-height”
<code class="language-css">p { min-height: 50px;height:auto !important;height:50px;} </code>

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