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border-block-start-color

This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The border-block-start-color CSS property defines the color of the logical block-start border of an element, which maps to a physical border color depending on the element's writing mode, directionality, and text orientation. It corresponds to the border-top-color, border-right-color, border-bottom-color, or border-left-color property depending on the values defined for writing-mode, direction, and text-orientation.

Syntax

border-block-start-color: blue;
border-block-start-color: #4c5d21;

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

Initial value	`currentcolor`
Applies to	all elements
Inherited	no
Media	visual
Computed value	computed color
Animation type	discrete
Canonical order	the unique non-ambiguous order defined by the formal grammar

Values

<'color'>: See border-color

Formal syntax

<'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>

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-lr;
  border: 10px solid blue;
  border-block-start-color: red;
}

Specification

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

Browser compatibilityUpdate compatibility data on GitHub

	Desktop
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari
Basic support	69	No	41 41 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.	No	56	No

	Mobile
	Android webview	Chrome for Android	Edge Mobile	Firefox for Android	Opera for Android	iOS Safari	Samsung Internet
Basic support	69	?	No	41 41 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.	56	No	?