border-block-start-width

This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for the proper prefixes to use 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 spec changes.

Summary

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

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

Initial value	`medium`
Applies to	all elements
Inherited	no
Percentages	logical-width of containing block
Media	visual
Computed value	absolute length; `0` if the border style is `none` or `hidden`
Animatable	no
Canonical order	the unique non-ambiguous order defined by the formal grammar

Syntax

/* One-value syntax */
border-block-start-width: width
border-block-start-width: 5px;

/* Two-value syntax */
border-block-start-width: horizontal vertical
border-block-start-width: 0.3em 0 9px;

/* Three-value syntax */
border-block-start-width: top horizontal bottom
border-block-start-width: 0.3em 0 9px thick;

/* Four-value syntax */
border-block-start-width: top right bottom left
border-block-start-width: 0.3em 0 9px thick 1em;

border-block-start-width: inherit

Values

<'border-width'>: See border-width

Formal syntax

<'border-width'>

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: 1px solid blue;
  border-block-start-width: 5px;
}

Specification

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

Feature	Chrome	Firefox (Gecko)	Internet Explorer	Opera	Safari (WebKit)
Basic support	Not supported	41.0 (41.0)^[1]	Not supported	Not supported	Not supported

Feature	Android	Firefox Mobile (Gecko)	IE Phone	Opera Mobile	Safari Mobile
Basic support	Not supported	41.0 (41.0)^[1]	Not supported	Not supported	Not supported

[1] Available since Gecko 38, but behind the preference layout.css.vertical-text.enabled, then disabled by default.

border-block-start-width

Summary

Syntax

Values

Formal syntax

Example

HTML Content

CSS Content

Specification

Browser compatibility

See also

Document Tags and Contributors