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border-block-start

This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.

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. border-block-start can be used to set the values for one or more of: border-block-start-width, border-block-start-style, border-block-start-color. It maps to a physical border depending 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.

It relates to border-block-end, border-inline-start, and border-inline-end, which define the other borders of the element.

Initial value as each of the properties of the shorthand:
Applies to all elements
Inherited no
Media visual
Computed value as each of the properties of the shorthand:
Animation type discrete
Canonical order the unique non-ambiguous order defined by the formal grammar

Syntax

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

Values

One or more of the following, in any order:

<'border-width'>
See border-width
<'border-style'>
See border-style
<'color'>
See color

Formal syntax

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

where
<color> = <rgb()> | <rgba()> | <hsl()> | <hsla()> | <hex-color> | <named-color> | currentcolor | <deprecated-system-color>

where
<rgb()> = rgb( <rgb-component>#{3} )
<rgba()> = rgba( <rgb-component>#{3} , <alpha-value> )
<hsl()> = hsl( <hue>, <percentage>, <percentage> )
<hsla()> = hsla( <hue>, <percentage>, <percentage>, <alpha-value> )
<named-color> = <ident>
<deprecated-system-color> = ActiveBorder | ActiveCaption | AppWorkspace | Background | ButtonFace | ButtonHighlight | ButtonShadow | ButtonText | CaptionText | GrayText | Highlight | HighlightText | InactiveBorder | InactiveCaption | InactiveCaptionText | InfoBackground | InfoText | Menu | MenuText | Scrollbar | ThreeDDarkShadow | ThreeDFace | ThreeDHighlight | ThreeDLightShadow | ThreeDShadow | Window | WindowFrame | WindowText

where
<rgb-component> = <integer> | <percentage>
<alpha-value> = <number>
<hue> = <number>

Example

HTML Content

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

CSS Content

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

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

Specification

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

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support No support 41.0 (41.0)[1] No support No support No support
Feature Android Firefox Mobile (Gecko) IE Phone Opera Mobile Safari Mobile
Basic support No support 41.0 (41.0)[1] No support No support No support

[1] Available since Gecko 38, but behind the preference layout.css.vertical-text.enabled, then disabled by default. The preference has been removed in Gecko 51 and this property cannot be disabled since this version.

See also

© 2005–2017 Mozilla Developer Network 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-block-start