在此页

• 基本规则句法
• 索引
• 选择器
• 概念
• DOM-CSS / CSSOM
• 另请参阅
• 外部链接
• 相关话题

使用此 CSS 参考 来浏览 按字母顺序索引 的所有标准 CSS 特性， pseudo-classes , pseudo-elements , 数据类型 , 函数表示法 and at-rules 。您还可以浏览 关键 CSS 概念 和列表化的 按类型组织的选择器 。还包括简要 DOM-CSS / CSSOM 参考 .

基本规则句法

样式规则句法

style-rule ::=
    selectors-list {
      properties-list
    }
					

... where :

selectors-list ::=
    selector[:pseudo-class] [::pseudo-element]
    [, selectors-list]
properties-list ::=
    [property : value] [; properties-list]
					

See the index of selectors , pseudo-classes ，和 pseudo-elements below. The syntax for each specified value depends on the data type defined for each specified property .

样式规则范例

strong {
  color: red;
}
div.menu-bar li:hover > ul {
  display: block;
}
					

For a beginner-level introduction to the syntax of selectors, see our guide on CSS Selectors . Be aware that any syntax error in a rule definition invalidates the entire rule. Invalid rules are ignored by the browser. Note that CSS rule definitions are entirely (ASCII) text-based , whereas DOM-CSS / CSSOM (the rule management system) is object-based .

At-rule syntax

As the structure of at-rules varies widely, please see At-rule to find the syntax of the specific one you want.

索引

注意： The property names in this index do not include the JavaScript 名称 where they differ from the CSS standard names.

选择器

The following are the various selectors , which allow styles to be conditional based on various features of elements within the DOM.

基本选择器

基本选择器 are fundamental selectors; these are the most basic selectors that are frequently combined to create other, more complex selectors.

• Universal selector * , ns|* , *|* , |*
• 类型选择器 elementname
• 类选择器 . classname
• ID 选择器 # idname
• 属性选择器 [ attr = value ]

分组选择器

选择器列表 A , B

Specifies that both A and B elements are selected. This is a grouping method to select several matching elements.

组合器

Combinators are selectors that establish a relationship between two or more simple selectors, such as " A is a child of B " or " A is adjacent to B ."

Adjacent sibling combinator A + B

Specifies that the elements selected by both A and B have the same parent and that the element selected by B immediately follows the element selected by A horizontally.

General sibling combinator A ~ B

Specifies that the elements selected by both A and B share the same parent and that the element selected by A comes before—but not necessarily immediately before—the element selected by B .

Child combinator A > B

Specifies that the element selected by B is the direct child of the element selected by A .

Descendant combinator A B

Specifies that the element selected by B is a descendant of the element selected by A , but is not necessarily a direct child.

Column combinator A || B

Specifies that the element selected by B is located within the table column specified by A . Elements which span multiple columns are considered to be a member of all of those columns.

Pseudo

Pseudo classes :

Specifies a special state of the selected element(s).

Pseudo elements ::

Represents entities that are not included in HTML.

另请参阅： Selectors in the Selectors Level 4 specification .

概念

句法和语义

• CSS 句法
• At-rules
• Cascade
• 注释
• 描述符
• 继承
• 简写特性
• 特异性
• 值定义句法
• CSS unit and value types
• CSS functional notations

值

• 实际值
• 计算值
• 初始值
• 解析值
• 指定值
• 使用值

Layout

• 块格式化上下文
• Box 模型
• Containing block
• Layout mode
• Margin collapsing
• Replaced elements
• Stacking context
• Visual formatting model

DOM-CSS / CSSOM

主要对象类型

• DocumentOrShadowRoot.styleSheets
• styleSheets [i]. cssRules
• cssRules[i]. cssText (选择器 & 样式)
• cssRules[i]. selectorText
• HTMLElement.style
• HTMLElement.style. cssText (仅仅样式)
• Element.className
• Element.classList

重要方法

• CSSStyleSheet.insertRule()
• CSSStyleSheet.deleteRule()

另请参阅

• Mozilla CSS 扩展 (前缀采用 -moz- )
• WebKit CSS 扩展 (大多前缀采用 -webkit- )
• 微软 CSS 扩展 (前缀采用 -ms- )

外部链接

• CSS Indices (w3.org)

• 最后修改： Nov 8, 2020

相关话题

1. CSS
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