border-block-start

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since January 2020.

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.

Try it

border-block-start: solid; writing-mode: horizontal-tb; 
border-block-start: dashed red; writing-mode: vertical-rl; 
border-block-start: 1rem solid; writing-mode: horizontal-tb; 
border-block-start: thick double #32a1ce; writing-mode: vertical-lr; 
<section class="default-example" id="default-example"> <div class="transition-all" id="example-element"> This is a box with a border around it. </div> </section> 
#example-element { background-color: #eee; color: #8b008b; padding: 0.75em; width: 80%; height: 100px; unicode-bidi: bidi-override; }

Constituent properties

This property is a shorthand for the following CSS properties:

Syntax

css
border-block-start: 1px; border-block-start: 2px dotted; border-block-start: medium dashed blue; /* Global values */ border-block-start: inherit; border-block-start: initial; border-block-start: revert; border-block-start: revert-layer; border-block-start: unset;

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.

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-block-start = 
 <line-width> ||
 <line-style> ||
 <color> 

<line-width> = 
 <length [0,∞]> |
 thin |
 medium |
 thick 

<line-style> = 
 none |
 hidden |
 dotted |
 dashed |
 solid |
 double |
 groove |
 ridge |
 inset |
 outset

Examples

Border with vertical text

HTML

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

CSS

css
div { background-color: yellow; width: 120px; height: 120px; } .exampleText { writing-mode: vertical-rl; border-block-start: 5px dashed blue; }

Specifications

Specification
CSS Logical Properties and Values Level 1
# border-shorthands

Browser compatibility

See also