我們的志工尚未將此文章翻譯為 正體中文 (繁體) 版本。加入我們，幫忙翻譯！
Summary
The border-bottom CSS property is a shorthand that sets the values of border-bottom-color, border-bottom-style, and border-bottom-width. These properties describe the bottom border of elements.
The three values of the shorthand property can be specified in any order, and one or two of them may be omitted.
As with all shorthand properties, border-bottom always sets the values of all of the properties that it can set, even if they are not specified. It sets those that are not specified to their default values. This means that:
border-bottom-style: dotted; border-bottom: thick green;is actually the same as
border-bottom-style: dotted; border-bottom: none thick green;and the value of
border-bottom-style given before border-bottom is ignored.
Since the default value of border-bottom-style is none, not specifying the border-style part of the value means that the property specifies its default value which is none and means no border.
| Initial value | as each of the properties of the shorthand:
|
|---|---|
| Applies to | all elements. It also applies to ::first-letter. |
| Inherited | no |
| Media | visual |
| Computed value | as each of the properties of the shorthand:
|
| Animation type | as each of the properties of the shorthand:
|
| Canonical order | order of appearance in the formal grammar of the values |
Syntax
border-bottom: 1px; border-bottom: 2px dotted; border-bottom: medium dashed blue;
Values
<br-width>- See
border-bottom-width. <br-style>- See
border-bottom-style. <color>- See
border-bottom-color.
Formal syntax
<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 | WindowTextwhere
<rgb-component> = <integer> | <percentage>
<alpha-value> = <number>
<hue> = <number>
Examples
element {
border-bottom: 1px solid #000;
}
Specifications
| Specification | Status | Comment |
|---|---|---|
| CSS Backgrounds and Borders Module Level 3 The definition of 'border-bottom' in that specification. |
Candidate Recommendation | No direct changes, though the modification of values for the border-bottom-color do apply to it. |
| CSS Level 2 (Revision 1) The definition of 'border-bottom' in that specification. |
Recommendation | No significant changes |
| CSS Level 1 The definition of 'border-bottom' in that specification. |
Recommendation | Initial definition |
Browser compatibility
| 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) |