| [DHTMLET®](http://www.dhtmlet.com) | [伪对象清单 ](#)| 相关内容：SEE ALSO------------------------------------------ :after------------------------------------------ include-source quotes countent counter-reset counter-increment |
|-----|-----|
:before版本：CSS2 兼容性：NONE
语法：
*Selector*** : before ****{*** sRules ***}**
说明：
用来和[content](#)属性一起使用，设置在对象前（依据对象树的逻辑结构）发生的内容。
目前IE5.5尚不支持此伪对象。
示例：
em:before { content: url("ding.wav") }
苏沈小雨制作・保留所有权利
©2001 rain1977.comer . All rights reserved . Terms of Use .
- 简介 Introducing
- 样式表简介 Introduction to CSS2
- 关于本手册 About this handbook
- 苏沈小雨 About rain1977
- 属性 Properties
- 字体 Font
- font
- color
- font-family
- font-size
- font-size-adjust
- font-stretch
- font-style
- font-weight
- text-decoration
- text-underline-position
- text-shadow
- font-variant
- text-transform
- line-height
- letter-spacing
- word-spacing
- 文本 Text
- text-indent
- text-overflow
- vertical-align
- text-align
- layout-flow
- writing-mode
- direction
- unicode-bidi
- word-break
- line-break
- white-space
- word-wrap
- text-autospace
- text-kashida-space
- text-justify
- ruby-align
- ruby-overhang
- ruby-position
- ime-mode
- layout-grid
- layout-grid-char
- layout-grid-char-spacing
- layout-grid-line
- layout-grid-mode
- layout-grid-type
- 背景 Background
- background
- background-attachment
- background-color
- background-image
- background-position
- background-positionX
- background-positionY
- background-repeat
- layer-background-color
- layer-background-image
- 定位 Positioning
- position
- z-index
- top
- right
- bottom
- left
- 尺寸 Dimensions
- height
- max-height
- min-height
- width
- max-width
- min-width
- 布局 Layout
- clear
- float
- clip
- overflow
- overflow-x
- overflow-y
- display
- visibility
- 外补丁 Margins
- margin
- margin-top
- margin-right
- margin-bottom
- margin-left
- 轮廓 Outlines
- outline
- outline-color
- outline-style
- outline-width
- 边框 border
- border
- border-color
- border-style
- border-width
- border-top
- border-top-color
- border-top-style
- border-top-width
- border-right
- border-right-color
- border-right-style
- border-right-width
- border-bottom
- border-bottom-color
- border-bottom-style
- border-bottom-width
- border-left
- border-left-color
- border-left-style
- border-left-width
- 内容 Generated Content
- include-source
- quotes
- content
- counter-increment
- counter-reset
- 内补丁 Paddings
- padding
- padding-top
- padding-right
- padding-bottom
- padding-left
- 列表 Lists
- list-style
- list-style-image
- list-style-position
- list-style-type
- marker-offset
- 表格 table
- border-collapse
- border-spacing
- caption-side
- empty-cells
- table-layout
- speak-header
- 滚动条 Scrollbar
- scrollbar-3d-light-color
- scrollbar-highlight-color
- scrollbar-face-color
- scrollbar-arrow-color
- scrollbar-shadow-color
- scrollbar-dark-shadow-color
- scrollbar-base-color
- 打印 Printing
- page
- page-break-after
- page-break-before
- page-break-inside
- marks
- orphans
- size
- widows
- 声音 Aural
- voice-family
- volume
- elevation
- azimuth
- stress
- richness
- speech-rate
- cue
- cue-after
- cue-before
- pause
- pause-after
- pause-before
- pitch
- pitch-range
- play-during
- speak
- speak-numeral
- speak-punctuation
- 其它 Classification
- cursor
- behavior
- filter
- zoom
- 选择符 Selectors
- 通配选择符 Universal Selector
- 类型选择符 Type Selectors
- 属性选择符 Attribute Selectors
- 包含选择符 Descendant Selectors
- 子对象选择符 Child Selectors
- ID选择符 ID Selectors
- 类选择符 Class Selectors
- 选择符分组 Grouping
- 伪类 Pseudo-Classes
- :link
- :hover
- :active
- :visited
- :focus
- :first-letter
- :first-line
- :first-child
- :first
- :left
- :right
- :lang
- 伪对象 Pseudo-Elements
- :before
- :after
- 规则 At-Rules
- @import
- @charset
- @font-face
- @fontdef
- @page
- @media
- 声明 Declaration
- !important
- 单位 Units
- 长度 Length
- px
- em
- ex
- pt
- pc
- in
- mm
- cm
- 颜色 Color
- rgb(RGB)
- #RRGGBB
- Color Name
- 角度 Angle
- deg
- grad
- rad
- 时间 Time
- s
- ms
- 频率 Frequency
- Hz
- kHz
- 附录 Appendix
- 颜色表 Color Table
- 设备类型 Media Types
- 字符集识别 Character Set Recognition
- ISO Latin-1字符集 ISO Latin-1 Character Set
- HTML附加命名实体
- 特殊文本和BIDI文本的字符实体