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border-bottom

The border-bottom shorthand CSS property sets an element's bottom border. It sets the values of border-bottom-width, border-bottom-style and border-bottom-color.

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 results in no border.

Constituent properties

This property is a shorthand for the following CSS properties:

Syntax

border-bottom: 1px;
border-bottom: 2px dotted;
border-bottom: medium dashed blue;

The three values of the shorthand property can be specified in any order, and one or two of them may be omitted.

Values

<br-width>
See border-bottom-width.
<br-style>
See border-bottom-style.
<color>
See border-bottom-color.

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> || <line-style> || <color>

where
<line-width> = <length> | thin | medium | thick
<line-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( <percentage>{3} [ / <alpha-value> ]? ) | rgb( <number>{3} [ / <alpha-value> ]? ) | rgb( <percentage>#{3} , <alpha-value>? ) | rgb( <number>#{3} , <alpha-value>? )
<rgba()> = rgba( <percentage>{3} [ / <alpha-value> ]? ) | rgba( <number>{3} [ / <alpha-value> ]? ) | rgba( <percentage>#{3} , <alpha-value>? ) | rgba( <number>#{3} , <alpha-value>? )
<hsl()> = hsl( <hue> <percentage> <percentage> [ / <alpha-value> ]? ) | hsl( <hue>, <percentage>, <percentage>, <alpha-value>? )
<hsla()> = hsla( <hue> <percentage> <percentage> [ / <alpha-value> ]? ) | hsla( <hue>, <percentage>, <percentage>, <alpha-value>? )

where
<alpha-value> = <number> | <percentage>
<hue> = <number> | <angle>

Examples

Applying a bottom border

HTML

<div>
  This box has a border on the bottom side.
</div>

CSS

div {
  border-bottom: 4px dashed blue;
  background-color: gold;
  height: 100px;
  width: 100px;
  font-weight: bold;
  text-align: center;
}

Results

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 compatibilityUpdate compatibility data on GitHub

Desktop
Chrome Edge Firefox Internet Explorer Opera Safari
border-bottom 1 12 1 4 3.5 1
Mobile
Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
border-bottom 1 18 4 14 1 1.0

See also

© 2005–2020 Mozilla and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/CSS/border-bottom