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.
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 |
| Animation type | discrete |
| Canonical order | the unique non-ambiguous order defined by the formal grammar |
Syntax
/* border-block-start-width: width */ border-block-start-width: 5px; 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 |
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
- The mapped physical properties:
border-top-width,border-right-width,border-bottom-width, andborder-left-width writing-mode,direction,text-orientation