border-bottom-width

The border-bottom-width CSS property sets the width of the bottom border of a box.

/* Any <length> value */
border-bottom-width: 10em;
border-bottom-width: 3vmax;
border-bottom-width: 6px;
/* A keyword */
border-bottom-width: thin;
border-bottom-width: medium;
border-bottom-width: thick;
border-bottom-width: inherit;

Initial valuemedium
Applies toall elements. It also applies to ::first-letter.
Inheritedno
Mediavisual
Computed valuethe absolute length or 0 if border-bottom-style is none or hidden
Animation typea length
Canonical orderthe unique non-ambiguous order defined by the formal grammar

Syntax

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:
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
Represents the calculated value of the border-bottom-width of the parent's element.

Formal syntax

<br-width>

where
<br-width> = <length> | thin | medium | thick

Examples

element { 
    border-bottom-width: thin;
    border-bottom-style: solid;
    border-bottom-color: #000;
}

Specifications

Specification Status Comment
CSS Backgrounds and Borders Module Level 3
The 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 Initial definition

Browser compatibility

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 1.0 (Yes) 1.0 (1.0) 4.0 3.5 1.0 (85)

See also