border-block-start

The border-block-start CSS property is a shorthand property for setting the individual logical block-start border property values in a single place in the style sheet.

Constituent properties

This property is a shorthand for the following CSS properties:

Syntax

border-block-start: 1px;
border-block-start: 2px dotted;
border-block-start: medium dashed blue;

border-block-start can be used to set the values for one or more of border-block-start-width, border-block-start-style, and border-block-start-color. The physical border to which it maps depends on the element's writing mode, directionality, and text orientation. It corresponds to the border-top, border-right, border-bottom, or border-left property depending on the values defined for writing-mode, direction, and text-orientation.

Related properties are border-block-end, border-inline-start, and border-inline-end, which define the other borders of the element.

Values

The border-block-start is specified with one or more of the following, in any order:

<'border-width'>
The width of the border. See border-width.
<'border-style'>
The line style of the border. See border-style.
<'color'>
The color of the border. See color.

Formal definition

Initial valueas each of the properties of the shorthand:
Applies toall elements
Inheritedno
Computed valueas each of the properties of the shorthand:
Animation typeas each of the properties of the shorthand:

Formal syntax

<'border-top-width'> || <'border-top-style'> || <'color'>

where
<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

Border with vertical text

HTML

<div>
  <p class="exampleText">Example text</p>
</div>

CSS

div {
  background-color: yellow;
  width: 120px;
  height: 120px;
}

.exampleText {
  writing-mode: vertical-rl;
  border-block-start: 5px dashed blue;
}

Specifications

Specification Status Comment
CSS Logical Properties and Values Level 1
The definition of 'border-block-start' in that specification.
Editor's Draft Initial definition

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
border-block-startChrome Full support 69Edge Full support 79Firefox Full support 41
Full support 41
No support 38 — 51
Disabled
Disabled From version 38 until version 51 (exclusive): this feature is behind the layout.css.vertical-text.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config.
IE No support NoOpera Full support 56Safari Full support 12.1WebView Android Full support 69Chrome Android Full support 69Firefox Android Full support 41
Full support 41
No support 38 — 51
Disabled
Disabled From version 38 until version 51 (exclusive): this feature is behind the layout.css.vertical-text.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config.
Opera Android Full support 48Safari iOS Full support 12.2Samsung Internet Android Full support 10.0

Legend

Full support  
Full support
No support  
No support
User must explicitly enable this feature.
User must explicitly enable this feature.

See also