offset-block-start

This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The offset-block-start CSS property defines the logical block start offset of an element, which maps to a physical offset depending on the element's writing mode, directionality, and text orientation. It corresponds to the toprightbottom, or left property depending on the values defined for writing-mode, direction, and text-orientation.

/* <length> values */
offset-block-start: 3px;
offset-block-start: 2.4em;

/* <percentage>s of the width or height of the containing block */
offset-block-start: 10%;

/* Keyword value */
offset-block-start: auto;

/* Global values */
offset-block-start: inherit;
offset-block-start: initial;
offset-block-start: unset;

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

Initial valueauto
Applies topositioned elements
Inheritedno
Percentageslogical-height of containing block
Mediavisual
Computed valuesame as box offsets: top, right, bottom, left properties except that directions are logical
Animation typediscrete
Canonical orderthe unique non-ambiguous order defined by the formal grammar

Syntax

Values

The offset-block-start property takes the same values as the left property.

Formal syntax

<'left'>

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;
  position: relative;
  offset-block-start: 20px;
  background-color: #c8c800;
}

Specification

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

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support No ?

41

38 — 511

No No No
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support No ? ?

41

38 — 511

No No ?

1. From version 38 until version 51 (exclusive): this feature is behind the layout.css.vertical-text.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config.

See also

Document Tags and Contributors

 Contributors to this page: fscholz, rwilson.or, teoli, Sebastianz, kscarfone
 Last updated by: fscholz,