CSS border-block-start-width Property
Example
Set a width for the border at the start in the block direction:
div {
border-block-start-style: solid;
border-block-start-width: 10px;
}
Try it Yourself »
More "Try it Yourself" examples below.
Definition and Usage
The border-block-start-width property sets the width of an element's border at the start in the block direction.
Note: For the border-block-start-width property to take effect, the border-block-start-style property must be set.
The CSS
border-block-start-width property is very similar to CSS properties
border-bottom-width,
border-left-width,
border-right-width and
border-top-width, but the
border-block-start-width property is dependent on block direction.
Note: The related CSS property
writing-mode defines block direction. This affects where the start and end of a block is and the result of the border-block-start-width property. For pages in English, inline direction is left to right and block direction is downward.
| Default value: | medium |
|---|---|
| Inherited: | no |
| Animatable: | yes. Read about animatable Try it |
| Version: | CSS3 |
| JavaScript syntax: | object.style.borderBlockStartWidth="10px" Try it |
Browser Support
The numbers in the table specify the first browser version that fully supports the property.
| Property | |||||
|---|---|---|---|---|---|
| border-block-start-width | 69.0 | 79.0 | 41.0 | 12.1 | 56.0 |
CSS Syntax
border-block-start-width: medium|thin|thick|length|initial|inherit;
Property Values
| Value | Description | Demo |
|---|---|---|
| medium | Specifies a medium border. This is default | Demo ❯ |
| thin | Specifies a thin border | Demo ❯ |
| thick | Specifies a thick border | Demo ❯ |
| length | Allows you to define the thickness of the border. Read about length units | Demo ❯ |
| initial | Sets this property to its default value. Read about initial | |
| inherit | Inherits this property from its parent element. Read about inherit |
More Examples
With writing-mode property
The position of the border width at the start in the block direction is affected by the writing-mode property:
div {
border-block-start-style: solid;
writing-mode: vertical-rl;
border-block-start-width: 5px;
}
Try it Yourself »
Related Pages
CSS tutorial: CSS Border
CSS border property: CSS Border property
CSS border-block property: CSS Border-block property
CSS border-block-width property: CSS Border-block-width property
CSS border-block-end-width property: CSS Border-block-end-width property
CSS border-bottom-width property: CSS Border-bottom-width property
CSS border-left-width property: CSS Border-left-width property
CSS border-right-width property: CSS Border-right-width property
CSS border-top-width property: CSS Border-top-width property
CSS writing-mode property: CSS Writing-mode property
