Html 了解CSS选择器优先级/特异性

我想了解CSS选择器如何处理属性冲突。如何选择一个属性而不是另一个属性

  <!-- start class vs id -->
  <p class="class1" id="id1">.class vs #id: The winner is #id</p>

  <!-- upper vs bottom -->
  <p id="id2">the very bottom is the winner</p>

  <!--most specific is the winner -->
  <p id="id3">the most specific</p>

  <!--pseudo and target selector -->
  <h3>pseudo vs type selector</h3>

  <!-- !important is more important! -->
  <h1 id="very-specific">HI! I am very important!</h1>
  </body>

div{
背景色：红色；
}
我的班级{
背景色：黑色；
}
div#我的id{
背景颜色：蓝色；
}
身体科{
背景颜色：绿色；
}
正文>div{
背景颜色：橙色；
}
body>div#我的id{
背景颜色：粉红色；
}

---

您好

您感兴趣的是

  <!-- start class vs id -->
  <p class="class1" id="id1">.class vs #id: The winner is #id</p>

  <!-- upper vs bottom -->
  <p id="id2">the very bottom is the winner</p>

  <!--most specific is the winner -->
  <p id="id3">the most specific</p>

  <!--pseudo and target selector -->
  <h3>pseudo vs type selector</h3>

  <!-- !important is more important! -->
  <h1 id="very-specific">HI! I am very important!</h1>
  </body>

---

Firebug是一个很好的工具来帮助检查这一点。但是其他浏览器也有内置的工具来检查应用的CSS规则。

您感兴趣的是

  <!-- start class vs id -->
  <p class="class1" id="id1">.class vs #id: The winner is #id</p>

  <!-- upper vs bottom -->
  <p id="id2">the very bottom is the winner</p>

  <!--most specific is the winner -->
  <p id="id3">the most specific</p>

  <!--pseudo and target selector -->
  <h3>pseudo vs type selector</h3>

  <!-- !important is more important! -->
  <h1 id="very-specific">HI! I am very important!</h1>
  </body>

---

Firebug是一个很好的工具来帮助检查这一点。但其他浏览器也有内置的工具，用于检查应用的CSS规则。

我将插入一个指向CSS 2.1规范本身的链接，以及浏览器应该如何计算特定性：

  <!-- start class vs id -->
  <p class="class1" id="id1">.class vs #id: The winner is #id</p>

  <!-- upper vs bottom -->
  <p id="id2">the very bottom is the winner</p>

  <!--most specific is the winner -->
  <p id="id3">the most specific</p>

  <!--pseudo and target selector -->
  <h3>pseudo vs type selector</h3>

  <!-- !important is more important! -->
  <h1 id="very-specific">HI! I am very important!</h1>
  </body>

:

  <!-- start class vs id -->
  <p class="class1" id="id1">.class vs #id: The winner is #id</p>

  <!-- upper vs bottom -->
  <p id="id2">the very bottom is the winner</p>

  <!--most specific is the winner -->
  <p id="id3">the most specific</p>

  <!--pseudo and target selector -->
  <h3>pseudo vs type selector</h3>

  <!-- !important is more important! -->
  <h1 id="very-specific">HI! I am very important!</h1>
  </body>

选择器的特异性计算如下：

  <!-- start class vs id -->
  <p class="class1" id="id1">.class vs #id: The winner is #id</p>

  <!-- upper vs bottom -->
  <p id="id2">the very bottom is the winner</p>

  <!--most specific is the winner -->
  <p id="id3">the most specific</p>

  <!--pseudo and target selector -->
  <h3>pseudo vs type selector</h3>

  <!-- !important is more important! -->
  <h1 id="very-specific">HI! I am very important!</h1>
  </body>

• 如果声明来自，则计数1是一个“样式”属性，而不是一个带选择器的规则，否则为0（=a）（在HTML中，元素“样式”属性的值是样式表规则。这些规则没有选择器，因此a=1、b=0、c=0和d=0。）
• 计算选择器中ID属性的数量（=b）
• 计算选择器中其他属性和伪类的数量（=c）
• 计算选择器中元素名称和伪元素的数量（=d）
• 特异性仅基于选择器的形式。特别是，形式为“[id=p33]”的选择器被计为属性选择器（a=0，b=0，c=1，d=0），即使id属性在源文档的DTD中定义为“id”

将四个数字a-b-c-d（在基数较大的数字系统中）串联在一起，给出了特殊性

  <!-- start class vs id -->
  <p class="class1" id="id1">.class vs #id: The winner is #id</p>

  <!-- upper vs bottom -->
  <p id="id2">the very bottom is the winner</p>

  <!--most specific is the winner -->
  <p id="id3">the most specific</p>

  <!--pseudo and target selector -->
  <h3>pseudo vs type selector</h3>

  <!-- !important is more important! -->
  <h1 id="very-specific">HI! I am very important!</h1>
  </body>

如果特殊性相同，则发挥作用：

  <!-- start class vs id -->
  <p class="class1" id="id1">.class vs #id: The winner is #id</p>

  <!-- upper vs bottom -->
  <p id="id2">the very bottom is the winner</p>

  <!--most specific is the winner -->
  <p id="id3">the most specific</p>

  <!--pseudo and target selector -->
  <h3>pseudo vs type selector</h3>

  <!-- !important is more important! -->
  <h1 id="very-specific">HI! I am very important!</h1>
  </body>

最后，按指定的顺序排序：如果两个声明具有相同的权重、来源和特定性，则后一个声明将获胜。导入的样式表中的声明被视为在样式表本身中的任何声明之前

---

请注意，这是指何时定义样式，而不是何时使用样式。如果类

.a

和

.b

具有相同的特异性，则以样式表中最后定义的为准<根据

.a

和

.b

的定义顺序，code>

…

和

…
的样式将是相同的，我将插入一个指向CSS 2.1规范本身的链接，以及浏览器应该如何计算特定性：

  <!-- start class vs id -->
  <p class="class1" id="id1">.class vs #id: The winner is #id</p>

  <!-- upper vs bottom -->
  <p id="id2">the very bottom is the winner</p>

  <!--most specific is the winner -->
  <p id="id3">the most specific</p>

  <!--pseudo and target selector -->
  <h3>pseudo vs type selector</h3>

  <!-- !important is more important! -->
  <h1 id="very-specific">HI! I am very important!</h1>
  </body>

:

  <!-- start class vs id -->
  <p class="class1" id="id1">.class vs #id: The winner is #id</p>

  <!-- upper vs bottom -->
  <p id="id2">the very bottom is the winner</p>

  <!--most specific is the winner -->
  <p id="id3">the most specific</p>

  <!--pseudo and target selector -->
  <h3>pseudo vs type selector</h3>

  <!-- !important is more important! -->
  <h1 id="very-specific">HI! I am very important!</h1>
  </body>

选择器的特异性计算如下：

  <!-- start class vs id -->
  <p class="class1" id="id1">.class vs #id: The winner is #id</p>

  <!-- upper vs bottom -->
  <p id="id2">the very bottom is the winner</p>

  <!--most specific is the winner -->
  <p id="id3">the most specific</p>

  <!--pseudo and target selector -->
  <h3>pseudo vs type selector</h3>

  <!-- !important is more important! -->
  <h1 id="very-specific">HI! I am very important!</h1>
  </body>


如果声明来自，则计数1是一个“样式”属性，而不是一个带选择器的规则，否则为0（=a）（在HTML中，元素“样式”属性的值是样式表规则。这些规则没有选择器，因此a=1、b=0、c=0和d=0。）
计算选择器中ID属性的数量（=b）
计算选择器中其他属性和伪类的数量（=c）
计算选择器中元素名称和伪元素的数量（=d）
特异性仅基于选择器的形式。特别是，形式为“[id=p33]”的选择器被计为属性选择器（a=0，b=0，c=1，d=0），即使id属性在源文档的DTD中定义为“id”

将四个数字a-b-c-d（在基数较大的数字系统中）串联在一起，给出了特殊性

  <!-- start class vs id -->
  <p class="class1" id="id1">.class vs #id: The winner is #id</p>

  <!-- upper vs bottom -->
  <p id="id2">the very bottom is the winner</p>

  <!--most specific is the winner -->
  <p id="id3">the most specific</p>

  <!--pseudo and target selector -->
  <h3>pseudo vs type selector</h3>

  <!-- !important is more important! -->
  <h1 id="very-specific">HI! I am very important!</h1>
  </body>

如果特殊性相同，则发挥作用：

  <!-- start class vs id -->
  <p class="class1" id="id1">.class vs #id: The winner is #id</p>

  <!-- upper vs bottom -->
  <p id="id2">the very bottom is the winner</p>

  <!--most specific is the winner -->
  <p id="id3">the most specific</p>

  <!--pseudo and target selector -->
  <h3>pseudo vs type selector</h3>

  <!-- !important is more important! -->
  <h1 id="very-specific">HI! I am very important!</h1>
  </body>

最后，按指定的顺序排序：如果两个声明具有相同的权重、来源和特定性，则后一个声明将获胜。导入的样式表中的声明被视为在样式表本身中的任何声明之前
请注意，这是指何时定义样式，而不是何时使用样式。如果类
.a
和
.b
具有相同的特异性，则以样式表中最后定义的为准<根据
.a
和
.b
的定义顺序，code>
的样式将相同

  <!-- start class vs id -->
  <p class="class1" id="id1">.class vs #id: The winner is #id</p>

  <!-- upper vs bottom -->
  <p id="id2">the very bottom is the winner</p>

  <!--most specific is the winner -->
  <p id="id3">the most specific</p>

  <!--pseudo and target selector -->
  <h3>pseudo vs type selector</h3>

  <!-- !important is more important! -->
  <h1 id="very-specific">HI! I am very important!</h1>
  </body>

元素
类选择器
ID选择器
内联样式
!！重要的
按顺序，1为最低特异性，5为最高特异性。
将显示详细信息以演示它

  <!-- start class vs id -->
  <p class="class1" id="id1">.class vs #id: The winner is #id</p>

  <!-- upper vs bottom -->
  <p id="id2">the very bottom is the winner</p>

  <!--most specific is the winner -->
  <p id="id3">the most specific</p>

  <!--pseudo and target selector -->
  <h3>pseudo vs type selector</h3>

  <!-- !important is more important! -->
  <h1 id="very-specific">HI! I am very important!</h1>
  </body>

元素
类选择器
ID选择器
内联样式
!！重要的
按顺序，1为最低特异性，5为最高特异性。
将显示详细信息以进行演示。
您可以在此处参考完整答案

  <!-- start class vs id -->
  <p class="class1" id="id1">.class vs #id: The winner is #id</p>

  <!-- upper vs bottom -->
  <p id="id2">the very bottom is the winner</p>

  <!--most specific is the winner -->
  <p id="id3">the most specific</p>

  <!--pseudo and target selector -->
  <h3>pseudo vs type selector</h3>

  <!-- !important is more important! -->
  <h1 id="very-specific">HI! I am very important!</h1>
  </body>

从最具体的开始：
id选择器>类选择器>类型选择器（普通h1、p标记等）
!重要的总是赢，但这被认为是一个坏的做法。请参阅上面的链接

  <!-- start class vs id -->
  <p class="class1" id="id1">.class vs #id: The winner is #id</p>

  <!-- upper vs bottom -->
  <p id="id2">the very bottom is the winner</p>

  <!--most specific is the winner -->
  <p id="id3">the most specific</p>

  <!--pseudo and target selector -->
  <h3>pseudo vs type selector</h3>

  <!-- !important is more important! -->
  <h1 id="very-specific">HI! I am very important!</h1>
  </body>

最好的方法是进行试验：

  <!-- start class vs id -->
  <p class="class1" id="id1">.class vs #id: The winner is #id</p>

  <!-- upper vs bottom -->
  <p id="id2">the very bottom is the winner</p>

  <!--most specific is the winner -->
  <p id="id3">the most specific</p>

  <!--pseudo and target selector -->
  <h3>pseudo vs type selector</h3>

  <!-- !important is more important! -->
  <h1 id="very-specific">HI! I am very important!</h1>
  </body>

一个测试用例。
你可以在这里参考完整答案

  <!-- start class vs id -->
  <p class="class1" id="id1">.class vs #id: The winner is #id</p>

  <!-- upper vs bottom -->
  <p id="id2">the very bottom is the winner</p>

  <!--most specific is the winner -->
  <p id="id3">the most specific</p>

  <!--pseudo and target selector -->
  <h3>pseudo vs type selector</h3>

  <!-- !important is more important! -->
  <h1 id="very-specific">HI! I am very important!</h1>
  </body>

从最具体的开始：
id选择器>类选择器>类型选择器（普通h1、p标记等）
!重要的总是赢，但这被认为是一个坏的做法。请参阅上面的链接

  <!-- start class vs id -->
  <p class="class1" id="id1">.class vs #id: The winner is #id</p>

  <!-- upper vs bottom -->
  <p id="id2">the very bottom is the winner</p>

  <!--most specific is the winner -->
  <p id="id3">the most specific</p>

  <!--pseudo and target selector -->
  <h3>pseudo vs type selector</h3>

  <!-- !important is more important! -->
  <h1 id="very-specific">HI! I am very important!</h1>
  </body>

最好的方法是进行试验：

  <!-- start class vs id -->
  <p class="class1" id="id1">.class vs #id: The winner is #id</p>

  <!-- upper vs bottom -->
  <p id="id2">the very bottom is the winner</p>

  <!--most specific is the winner -->
  <p id="id3">the most specific</p>

  <!--pseudo and target selector -->
  <h3>pseudo vs type selector</h3>

  <!-- !important is more important! -->
  <h1 id="very-specific">HI! I am very important!</h1>
  </body>

一个测试用例。
Firebug是否有特定的（没有双关语）工具来分析特异性？比通过罢工查看被推翻的规则更重要吗？@Pekka，不，没有。尽管如此，这仍然是一个很好的工具。@Pekka在HTML选项卡的右侧，Calculated（？）选项卡（介于样式和外观之间）有另一个贯穿覆盖指令视图的工具。当您只对一个属性感兴趣时，它比您可能指的样式更有用。Firebug是否有特定的（没有双关语）工具来分析特定性？超过了覆盖规则的穿透视图？@Pe
  <!-- start class vs id -->
  <p class="class1" id="id1">.class vs #id: The winner is #id</p>

  <!-- upper vs bottom -->
  <p id="id2">the very bottom is the winner</p>

  <!--most specific is the winner -->
  <p id="id3">the most specific</p>

  <!--pseudo and target selector -->
  <h3>pseudo vs type selector</h3>

  <!-- !important is more important! -->
  <h1 id="very-specific">HI! I am very important!</h1>
  </body>