The border-bottom-width
CSS property sets the width of the bottom border of an element.
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Syntax
/* Keyword values */ border-bottom-width: thin; border-bottom-width: medium; border-bottom-width: thick; /* <length> values */ border-bottom-width: 10em; border-bottom-width: 3vmax; border-bottom-width: 6px; /* Global keywords */ border-bottom-width: inherit; border-bottom-width: initial; border-bottom-width: unset;
Values
<line-width>
- Defines the width of the border, either as an explicit nonnegative
<length>
or a keyword. If it's a keyword, it must be one of the following values:thin
A thin border medium
A medium border thick
A thick border Note: Because the specification doesn't define the exact thickness denoted by each keyword, the precise result when using one of them is implementation-specific. Nevertheless, they always follow the pattern
thin ≤ medium ≤ thick
, and the values are constant within a single document.
Formal definition
Initial value | medium
|
Applies to | all elements. It also applies to ::first-letter .
|
Inherited | no |
Computed value | the absolute length or 0 if border-bottom-style is none or hidden
|
Animation type | a length |
Formal syntax
<line-width>where <line-width> = <length> | thin | medium | thick
Examples
Comparing bottom border widths
HTML
<div>Element 1</div>
<div>Element 2</div>
CSS
div {
border: 1px solid red;
margin: 1em 0;
}
div:nth-child(1) {
border-bottom-width: thick;
}
div:nth-child(2) {
border-bottom-width: 2em;
}
Result
Specifications
Specification | Status | Comment |
---|---|---|
CSS Backgrounds and Borders Module Level 3The definition of 'border-bottom-width' in that specification. | Candidate Recommendation | No significant change. |
CSS Level 2 (Revision 1)The definition of 'border-bottom-width' in that specification. | Recommendation | No significant change. |
CSS Level 1The definition of 'border-bottom-width' in that specification. | Recommendation | Initial definition. |
Browser compatibility
The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Update compatibility data on GitHub
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
border-bottom-width
|
Chrome
Full support 1 |
Edge
Full support 12 |
Firefox
Full support 1 |
IE
Full support 4 |
Opera
Full support 3.5 |
Safari
Full support 1 |
WebView Android
Full support 2.3 |
Chrome Android
Full support 18 |
Firefox Android
Full support 4 |
Opera Android
Full support 10.1 |
Safari iOS
Full support 1 |
Samsung Internet Android
Full support 1.0 |
Legend
- Full support
- Full support
See also
- The other border-width-related CSS properties:
border-left-width
,border-right-width
,border-top-width
, andborder-width
. - The other border-bottom-related CSS properties:
border
,border-bottom
,border-bottom-style
, andborder-bottom-color
.
border-bottom-width by Mozilla Contributors is licensed under CC-BY-SA 2.5.