[CSS参考手册](http://css.doyoe.com/)»[单位列表](#)»[长度单位](#)»
相关内容：
[**其它长度单位参考**选择其它项](#)
- [em](#)
- [ex](#)
- [ch](#)
- [rem](#)
- [vw](#)
- [vh](#)
- [vm](#)
- [cm](#)
- [mm](#)
- [in](#)
- [pt](#)
- [pc](#)
- [px](#)
# ex
- **版本：CSS1**
### 说明：
**相对长度单位。相对于字符“x”的高度。通常为字体高度的一半。**
- 如当前对行内文本的字体尺寸未被人为设置，则相对于浏览器的默认字体尺寸。
### 兼容性：
- 浅绿 = 支持
- 红色 = 不支持
- 墨绿 = 部分支持
- 橙色 = 实验性质
| [支持版本](# "查看本文档测试时所用浏览器版本")\类型 | IE | Firefox | Safari | Chrome | Opera |
|-----|-----|-----|-----|-----|-----|
| 版本 | 6.0 | 4.0 | 5.1 | 13.0 | 11.50 |
### 示例：
# 定义一条与字母x高度相同的线：
xxxx
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- CSS3列表 CSS3 List
- 简介 Introduction
- 关于本手册 About This Handbook
- 关于样式表 Introduction To CSS
- 关于作者 About The Author
- 阅读及使用指引 The Use Guides
- 鸣谢 Thank You
- 捐赠 Contribute
- 属性 Properties
- 定位(Positioning)
- position
- z-index
- top
- right
- bottom
- left
- 布局(Layout)
- display
- float
- clear
- visibility
- clip
- overflow
- overflow-x
- overflow-y
- 弹性盒模型(Flexible Box)
- box-orient
- box-pack
- box-align
- box-flex
- box-flex-group
- box-ordinal-group
- box-direction
- box-lines
- 尺寸(Dimension)
- width
- min-width
- max-width
- height
- min-height
- max-height
- 外补白(Margin)
- margin
- margin-top
- margin-right
- margin-bottom
- margin-left
- 内补白(Padding)
- padding
- padding-top
- padding-right
- padding-bottom
- padding-left
- 边框(Border)
- border
- border-width
- border-style
- border-color
- border-top
- border-top-width
- border-top-style
- border-top-color
- border-right
- border-right-width
- border-right-style
- border-right-color
- border-bottom
- border-bottom-width
- border-bottom-style
- border-bottom-color
- border-left
- border-left-width
- border-left-style
- border-left-color
- border-image
- border-radius
- border-top-left-radius
- border-top-right-radius
- border-bottom-right-radius
- border-bottom-left-radius
- box-shadow
- box-reflect
- 背景(Background)
- background
- background-color
- background-image
- background-repeat
- background-attachment
- background-position
- background-origin
- background-clip
- background-size
- Multiple background
- 颜色(Color)
- color
- opacity
- 字体(Font)
- font
- font-style
- font-variant
- font-weight
- font-size
- font-family
- font-stretch
- 文本(Text)
- text-indent
- text-overflow
- text-align
- text-transform
- text-decoration
- text-decoration-line
- text-decoration-color
- text-decoration-style
- text-shadow
- text-fill-color
- text-stroke
- text-stroke-width
- text-stroke-color
- letter-spacing
- word-spacing
- vertical-align
- word-wrap
- white-space
- direction
- unicode-bidi
- line-height
- tab-size
- 列表(List)
- list-style
- list-style-image
- list-style-position
- list-style-type
- 表格(Table)
- table-layout
- border-collapse
- border-spacing
- caption-side
- empty-cells
- 内容(Content)
- content
- counter-increment
- counter-reset
- quotes
- 用户界面(User Interface)
- outline
- outline-width
- outline-color
- outline-style
- outline-offset
- nav-index
- nav-up
- nav-right
- nav-down
- nav-left
- cursor
- zoom
- box-sizing
- resize
- ime-mode
- 多栏(Multi-column)
- columns
- column-width
- column-count
- column-gap
- column-rule
- column-rule-width
- column-rule-style
- column-rule-color
- column-span
- column-fill
- column-break-before
- column-break-after
- column-break-inside
- 2D变换(2D Transform)
- transform
- transform-origin
- 过渡(Transition)
- transition
- transition-property
- transition-duration
- transition-timing-function
- transition-delay
- 动画(Animation)
- animation
- animation-name
- animation-duration
- animation-timing-function
- animation-delay
- animation-iteration-count
- animation-direction
- animation-play-state
- animation-fill-mode
- 打印(Printing)
- page
- page-break-before
- page-break-after
- page-break-inside
- 媒体查询(Media Queries)
- width
- height
- device-width
- device-height
- orientation
- aspect-ratio
- device-aspect-ratio
- color
- color-index
- monochrome
- resolution
- scan
- grid
- Only Ie
- scrollbar-3dlight-color
- scrollbar-darkshadow-color
- scrollbar-highlight-color
- scrollbar-shadow-color
- scrollbar-arrow-color
- scrollbar-base-color
- scrollbar-track-color
- scrollbar-face-color
- filter
- behavior
- Only Firefox
- border-colors
- border-top-colors
- border-right-colors
- border-bottom-colors
- border-left-colors
- 选择符 Selectors
- 元素选择符
- 通配选择符(*)
- 类型选择符(E)
- ID选择符(E#myid)
- 类选择符(E.myclass)
- 关系选择符
- 包含选择符(E F)
- 子选择符(E>F)
- 相邻选择符(E+F)
- 兄弟选择符(E~F)
- 属性选择符
- E[att]
- E[att="val"]
- E[att~="val"]
- E[att^="val"]
- E[att$="val"]
- E[att*="val"]
- E[att|="val"]
- 伪类选择符
- E:link
- E:visited
- E:hover
- E:active
- E:focus
- E:root
- E:first-child
- E:last-child
- E:only-child
- E:nth-child(n)
- E:nth-last-child(n)
- E:first-of-type
- E:last-of-type
- E:only-of-type
- E:nth-of-type(n)
- E:nth-last-of-type(n)
- E:empty
- E:checked
- E:enabled
- E:disabled
- E:target
- @page:first
- @page:left
- @page:right
- 伪对象选择符
- E:first-letter/E::first-letter
- E:first-line/E::first-line
- E:before/E::before
- E:after/E::after
- E::selection
- 语法与规则 Rules
- !important
- comment
- @import
- @charset
- @media
- @font-face
- @page
- @keyframes
- 取值 Values
- 颜色(Color)
- Color Name
- HEX
- RGB
- RGBA
- HSL
- HSLA
- transparent
- 文本(Textual)
- <string>
- <url>
- <identifier>
- 函数(Functional)
- 图像(Image)
- 数字(Numeric)
- <number>
- <integer>
- 其它(Other)
- <length>
- <percentage>
- <angle>
- <time>
- <frequency>
- <fraction>
- <grid>
- 单位 Units
- 长度(Length)
- em
- ex
- ch
- rem
- vw
- vh
- vm
- cm
- mm
- in
- pt
- pc
- px
- 角度(Angle)
- deg
- grad
- rad
- turn
- 时间(Time)
- s
- ms
- 频率(Frequency)
- Hz
- kHz
- 布局(Layout-specific)
- fr
- gr
- 附录 Appendix
- 颜色关键字(Color Keywods)
- 媒体类型(Media Types)
- CSS Hack
- 条件Hack
- 属性级Hack
- 选择符级Hack
- 问题与经验 Experience
- Bugs和解决方案
- 技巧和经验
- 其它经验