The border-width
shorthand CSS property sets the width of an element's border.
The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.
Constituent properties
This property is a shorthand for the following CSS properties:
Syntax
/* Keyword values */ border-width: thin; border-width: medium; border-width: thick; /* <length> values */ border-width: 4px; border-width: 1.2rem; /* vertical | horizontal */ border-width: 2px 1.5em; /* top | horizontal | bottom */ border-width: 1px 2em 1.5cm; /* top | right | bottom | left */ border-width: 1px 2em 0 4rem; /* Global keywords */ border-width: inherit; border-width: initial; border-width: unset;
The border-width
property may be specified using one, two, three, or four values.
- When one value is specified, it applies the same width to all four sides.
- When two values are specified, the first width applies to the top and bottom, the second to the left and right.
- When three values are specified, the first width applies to the top, the second to the left and right, the third to the bottom.
- When four values are specified, the widths apply to the top, right, bottom, and left in that order (clockwise).
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 | as each of the properties of the shorthand:
|
---|---|
Applies to | all elements. It also applies to ::first-letter . |
Inherited | no |
Computed value | as each of the properties of the shorthand:
|
Animation type | as each of the properties of the shorthand: |
Formal syntax
<line-width>{1,4}where
<line-width> = <length> | thin | medium | thick
Examples
A mix of values and lengths
HTML
<p id="sval"> one value: 6px wide border on all 4 sides</p> <p id="bival"> two different values: 2px wide top and bottom border, 10px wide right and left border</p> <p id="treval"> three different values: 0.3em top, 9px bottom, and zero width right and left</p> <p id="fourval"> four different values: "thin" top, "medium" right, "thick" bottom, and 1em left</p>
CSS
#sval { border: ridge #ccc; border-width: 6px; } #bival { border: solid red; border-width: 2px 10px; } #treval { border: dotted orange; border-width: 0.3em 0 9px; } #fourval { border: solid lightgreen; border-width: thin medium thick 1em; } p { width: auto; margin: 0.25em; padding: 0.25em; }
Result
Specifications
Specification | Status | Comment |
---|---|---|
CSS Backgrounds and Borders Module Level 3 The definition of 'border-width' in that specification. |
Candidate Recommendation | No direct change; the <length> CSS data type extension has an effect on this property. |
CSS Level 2 (Revision 1) The definition of 'border-width' in that specification. |
Recommendation | Added the constraint that values' meaning must be constant inside a document. |
CSS Level 1 The definition of 'border-width' in that specification. |
Recommendation | Initial definition. |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
border-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 | Chrome Android Full support 18 | Firefox Android Full support 4 | Opera Android Full support 10.1 | Safari iOS Full support 3 | Samsung Internet Android Full support 1.0 |
Legend
- Full support
- Full support
See also
- The border-related shorthand properties:
border
,border-style
,border-color
- The border-width-related properties:
border-bottom-width
,border-left-width
,border-right-width
,border-top-width