border-block-start

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.

{{InteractiveExample("CSS Demo: border-block-start")}}

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: #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:

• {{cssxref("border-block-start-color")}}
• {{cssxref("border-block-start-style")}}
• {{cssxref("border-block-start-width")}}

Syntax

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 {{cssxref("border-block-start-width")}}, {{cssxref("border-block-start-style")}}, and {{cssxref("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 {{cssxref("border-top")}}, {{cssxref("border-right")}}, {{cssxref("border-bottom")}}, or {{cssxref("border-left")}} property depending on the values defined for {{cssxref("writing-mode")}}, {{cssxref("direction")}}, and {{cssxref("text-orientation")}}.

Related properties are {{cssxref("border-block-end")}}, {{cssxref("border-inline-start")}}, and {{cssxref("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 {{cssxref("border-width")}}.
• <'border-style'>
  • : The line style of the border. See {{cssxref("border-style")}}.
• {{CSSXref("<color>")}}
  • : The color of the border.

Formal definition

{{CSSInfo}}

Formal syntax

{{csssyntax}}

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-start: 5px dashed blue;
}

{{EmbedLiveSample("Border_with_vertical_text", 140, 140)}}

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

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