border-bottom

在本文章中

摘要
语法
1. 值
2. 标准语法
示例
规则
浏览器支持状况

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摘要

border-bottom 简写属性把下边框的所有属性： border-bottom-color，border-bottom-style 与 border-bottom-width设置到了一个声明中。这些属性描述了元素的下边框样式。

border-bottom的三个简记属性可以以任意顺序排列, 并且它们中的任意一个都可以被省略.

与所有的简记属性相同， border-bottom 定义了它所有可以定义的属性，即使他们并没有被显式地定义。它把所有未被显式定义的参数都设置为了默认值，这意味着这些值将被定义为：

border-bottom-style: dotted;
border-bottom: thick green;

它和以下的代码是等价的：

border-bottom-style: dotted;
border-bottom: none thick green;

顺便一提，在 border-bottom 之前定义的 border-bottom-style的值因此被忽略了.

由于 border-bottom-style 并没有默认值, 未被定义的 border-style 参数的值将被设置为无，也就是无底边框.

初始值	as each of the properties of the shorthand: `border-bottom-width`: `medium` `border-bottom-style`: `none` `border-bottom-color`: `currentColor`
适用元素	all elements. It also applies to `::first-letter`.
是否是继承属性	否
适用媒体	visual
计算值	as each of the properties of the shorthand: `border-bottom-width`: the absolute length or `0` if `border-bottom-style` is `none` or `hidden` `border-bottom-style`: as specified `border-bottom-color`: If the value is translucent, the computed value will be the `rgba()` corresponding one. If it isn't, it will be the `rgb()` corresponding one. The `transparent` keyword maps to `rgba(0,0,0,0)`.
是否适用于 CSS 动画	as each of the properties of the shorthand: `border-bottom-color`: yes, as a color `border-bottom-style`: 否 `border-bottom-width`: yes, as a length
正规顺序	order of appearance in the formal grammar of the values

语法

border-bottom: 1px;
border-bottom: 2px dotted;
border-bottom: medium dashed blue;

值

<br-width>: 见 border-bottom-width.
<br-style>: 见 border-bottom-style.
<color>: 见 border-bottom-color.

标准语法

<br-width> || <br-style> || <color>where 
<br-width> = <length> | thin | medium | thick
<br-style> = none | hidden | dotted | dashed | solid | double | groove | ridge | inset | outset
<color> = <rgb()> | <rgba()> | <hsl()> | <hsla()> | <hex-color> | <named-color> | currentcolor | <deprecated-system-color>
where 
<rgb()> = rgb( <rgb-component>#{3} )
<rgba()> = rgba( <rgb-component>#{3} , <alpha-value> )
<hsl()> = hsl( <hue>, <percentage>, <percentage> )
<hsla()> = hsla( <hue>, <percentage>, <percentage>, <alpha-value> )
<named-color> = <ident>
<deprecated-system-color> = ActiveBorder | ActiveCaption | AppWorkspace | Background | ButtonFace | ButtonHighlight | ButtonShadow | ButtonText | CaptionText | GrayText | Highlight | HighlightText | InactiveBorder | InactiveCaption | InactiveCaptionText | InfoBackground | InfoText | Menu | MenuText | Scrollbar | ThreeDDarkShadow | ThreeDFace | ThreeDHighlight | ThreeDLightShadow | ThreeDShadow | Window | WindowFrame | WindowText
where 
<rgb-component> = <integer> | <percentage>
<alpha-value> = <number>
<hue> = <number>

示例

查看在线演示

element { 
  border-bottom: 1px solid #000;
}

规则

规则	状态	评价
CSS Backgrounds and Borders Module Level 3 border-bottom	Candidate Recommendation	没有直接的改变,即使 `border-bottom-color` 值的修改被确定.
CSS Level 2 (Revision 1) border-bottom	Recommendation	没有显著的变化
CSS Level 1 border-bottom	Recommendation	初始定义

Feature	Chrome	Firefox (Gecko)	Internet Explorer	Opera	Safari (WebKit)
Basic support	1.0	1.0 (1.7 or earlier)	4	3.5	1.0 (85)

Feature	Android	Firefox Mobile (Gecko)	IE Phone	Opera Mobile	Safari Mobile
Basic support	1.0	1.0 (1.0)	(Yes)	(Yes)	(Yes)

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最后编辑者: CauserLee, Nov 15, 2015, 4:58:42 AM

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