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/CSS

inset-block-start

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

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

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

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

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

Syntax

Values

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

Formal definition

Initial value auto
Applies to positioned elements
Inherited no
Percentages logical-height of containing block
Computed value same as box offsets: top, right, bottom, left properties except that directions are logical
Animation type a length, percentage or calc();

Formal syntax

<'top'>

Examples

Setting block start offset

HTML

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

CSS

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

.exampleText {
  writing-mode: vertical-lr;
  position: relative;
  inset-block-start: 20px;
  background-color: #c8c800;
}

Specifications

Browser compatibilityUpdate compatibility data on GitHub

Desktop
Chrome Edge Firefox Internet Explorer Opera Safari
inset-block-start 69
Disabled
69
Disabled
Disabled From version 69: this feature is behind the enable-experimental-web-platform-features preference (needs to be set to enabled). To change preferences in Chrome, visit chrome://flags.
79
Disabled
79
Disabled
Disabled From version 79: this feature is behind the enable-experimental-web-platform-features preference (needs to be set to enabled).
63
63
41 — 63
Uses the non-standard name: offset-block-start
38 — 51
Disabled
Disabled 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.
No 56
Disabled
56
Disabled
Disabled From version 56: this feature is behind the enable-experimental-web-platform-features preference (needs to be set to enabled).
No
Mobile
Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
inset-block-start No 69
Disabled
69
Disabled
Disabled From version 69: this feature is behind the enable-experimental-web-platform-features preference (needs to be set to enabled). To change preferences in Chrome, visit chrome://flags.
63
63
41 — 63
Uses the non-standard name: offset-block-start
38 — 51
Disabled
Disabled 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.
48
Disabled
48
Disabled
Disabled From version 48: this feature is behind the enable-experimental-web-platform-features preference (needs to be set to enabled).
No No

See also

© 2005–2020 Mozilla and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/CSS/inset-block-start