border-block CSS property

Try it

border-block: solid;
writing-mode: horizontal-tb;

border-block: dashed red;
writing-mode: vertical-rl;

border-block: 1rem solid;
writing-mode: horizontal-tb;
direction: rtl;

<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: #eeeeee;
  color: darkmagenta;
  padding: 0.75em;
  width: 80%;
  height: 100px;
  unicode-bidi: bidi-override;
}

Constituent properties

This property is a shorthand for the following CSS properties:

• border-block-color
• border-block-style
• border-block-width

Syntax

border-block: 1px;
border-block: 2px dotted;
border-block: medium dashed blue;

/* Global values */
border-block: inherit;
border-block: initial;
border-block: revert;
border-block: revert-layer;
border-block: unset;

Values

The border-block 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.

Description

border-block can be used to set the values for one or more of border-block-width, border-block-style, and border-block-color setting both the start and end in the block dimension at once. The physical borders to which it maps depends on the element's writing mode, directionality, and text orientation. It corresponds to the border-top and border-bottom or border-right, and border-left properties depending on the values defined for writing-mode, direction, and text-orientation.

The borders in the other dimension can be set with border-inline, which sets border-inline-start, and border-inline-end.

Formal definition

Formal syntax

border-block = 
  <'border-block-start'>  

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

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

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

Examples

Border with vertical text

HTML

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

CSS

div {
  background-color: yellow;
  width: 120px;
  height: 120px;
}

.exampleText {
  writing-mode: vertical-rl;
  border-block: 5px dashed blue;
}

Results

Specifications

Browser compatibility

See also

• CSS Logical Properties and Values
• This property maps to one of the physical border properties: border-top, border-right, border-bottom, or border-left.
• writing-mode, direction, text-orientation