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. border-block-start can be used to set the values for one or more of: border-block-start-width, border-block-start-style, border-block-start-color. It maps to a physical border depending on the element's writing mode, directionality, and text orientation. It corresponds to the border-top, border-right, border-bottom, or border-left property depending on the values defined for writing-mode, direction, and text-orientation.

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

Initial value	as each of the properties of the shorthand: border-width: as each of the properties of the shorthand: border-top-width: medium border-right-width: medium border-bottom-width: medium border-left-width: medium border-style: as each of the properties of the shorthand: border-top-style: none border-right-style: none border-bottom-style: none border-left-style: none color: Varies from one browser to another
Applies to	all elements
Inherited	no
Media	visual
Computed value	as each of the properties of the shorthand: border-width: as each of the properties of the shorthand: border-bottom-width: the absolute length or 0 if border-bottom-style is none or hidden border-left-width: the absolute length or 0 if border-left-style is none or hidden border-right-width: the absolute length or 0 if border-right-style is none or hidden border-top-width: the absolute length or 0 if border-top-style is none or hidden border-style: as each of the properties of the shorthand: border-bottom-style: as specified border-left-style: as specified border-right-style: as specified border-top-style: as specified color: If the value is translucent, the computed value will be the rgba() corresponding one. If it isn't, it will be the rgb() corresponding one. The transparent keyword maps to rgba(0,0,0,0).
Animation type	discrete
Canonical order	the unique non-ambiguous order defined by the formal grammar

Syntax

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

Values

One or more of the following, in any order:

<'border-width'>

See border-width

<'border-style'>

See border-style

<'color'>

See color

Formal syntax

<'border-width'> || <'border-style'> || <'color'>
where 
<color> = <rgb()> | <rgba()> | <hsl()> | <hsla()> | <hex-color> | <named-color> | currentcolor | <deprecated-system-color>
where 
<rgb()> = rgb( <rgb-component>#{3} )
<rgba()> = rgba( <rgb-component>#{3} , <alpha-value> )
<hsl()> = hsl( <hue>, <percentage>, <percentage> )
<hsla()> = hsla( <hue>, <percentage>, <percentage>, <alpha-value> )
<named-color> = <ident>
<deprecated-system-color> = ActiveBorder | ActiveCaption | AppWorkspace | Background | ButtonFace | ButtonHighlight | ButtonShadow | ButtonText | CaptionText | GrayText | Highlight | HighlightText | InactiveBorder | InactiveCaption | InactiveCaptionText | InfoBackground | InfoText | Menu | MenuText | Scrollbar | ThreeDDarkShadow | ThreeDFace | ThreeDHighlight | ThreeDLightShadow | ThreeDShadow | Window | WindowFrame | WindowText
where 
<rgb-component> = <integer> | <percentage>
<alpha-value> = <number>
<hue> = <number>

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-rl;
  border-block-start: 5px dashed blue;
}

Specification

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

Browser compatibility

[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, border-right, border-bottom, and border-left
• writing-mode, direction, text-orientation