border-width property

Definition and Usage

The border-width CSS property sets the width of the border of a box. Using the shorthand property border is often more convenient.

• Initialthe concatenation of the initial values of its longhand properties:
  • border-top-width: medium
  • border-right-width: medium
  • border-bottom-width: medium
  • border-left-width: medium
• Applies toall elements
• Inheritedno
• Mediavisual
• Computed Valueas each of the properties of the shorthand:
  • border-bottom-width: the absolute length or 0 if border-bottom-style is none or hidden
  • border-left-width: the absolute length or 0 if border-left-style is none or hidden
  • border-right-width: the absolute length or 0 if border-right-style is none or hidden
  • border-top-width: the absolute length or 0 if border-top-style is none or hidden
• Animatableas each of the properties of the shorthand:
  • border-bottom-width: yes, as a length
  • border-left-width: yes, as a length
  • border-right-width: yes, as a length
  • border-top-width: yes, as a length
• Canonical orderthe unique non-ambiguous order defined by the formal grammar

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Syntax

Formal syntax: <br-width>{1,4}

border-width: width                  /* One-value syntax */
border-width: horizontal vertical    /* Two-value syntax */
border-width: top vertical bottom    /* Three-value syntax */
border-width: top right bottom left  /* Four-value syntax */
border-width: inherit

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Values

<br-width>

Is either a non-negative explicit <length> value or a keyword denoting the thickness of the bottom border. The keyword must be one of the following values:

Style	Preview	Description
thin		A thin border
medium		A medium border
thick		A thick border

The specification doesn’t precisely define the thickness of each of the keywords, which is therefore implementation specific. Nevertheless, it requests that the thickness does follow the thin ≤ medium ≤ thick inequality and that the values are constant on a single document.

inherit

Is a keyword indicating that all four values are inherited from their parent’s element calculated value.

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Examples

border: ridge #ccc;
border-width: 6px;  /* same as "border: ridge #ccc 6px";  6px wide border on all 4 sides */

border: solid red;
border-width: 2px 10px;  /* 2px wide top and bottom border, 10px right and left border */

border: dotted orange;
border-width: 0.3em 0;   /* 0.3em wide top and bottom border, no border right and left */

border: solid lightgreen;
border-width: medium 0 1px thick;  /* three different width, no right border */

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Compatibility

Desktop browsers

Mobile browsers