inset-block CSS property

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

This inset property has no effect on non-positioned elements.

Try it

inset-block: 10px 20px;
writing-mode: horizontal-tb;
inset-block: 20px 40px;
writing-mode: vertical-rl;
inset-block: 5% 20%;
writing-mode: horizontal-tb;
inset-block: 1rem auto;
writing-mode: vertical-lr;
<section id="default-example">
  <div class="example-container">
    <div id="example-element">I am absolutely positioned.</div>
    <p>
      As much mud in the streets as if the waters had but newly retired from the
      face of the earth, and it would not be wonderful to meet a Megalosaurus,
      forty feet long or so, waddling like an elephantine lizard up Holborn
      Hill.
    </p>
  </div>
</section>
.example-container {
  border: 0.75em solid #ad1457;
  padding: 0.75em;
  text-align: left;
  position: relative;
  width: 100%;
  min-height: 200px;
}

#example-element {
  background-color: #07136c;
  border: 6px solid #ffa000;
  color: white;
  position: absolute;
  inset: 0;
}

Constituent properties

This property is a shorthand for the following CSS properties:

Syntax

css
/* <length> values */
inset-block: 3px 10px;
inset-block: 2.4em 3em;
inset-block: 10px; /* value applied to start and end */
inset-block: auto anchor(start);
inset-block: 10em anchor-size(--my-anchor height, 10%);

/* <percentage>s of the width or height of the containing block */
inset-block: 10% 5%;

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

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

Values

The inset-block property takes the same values as the top property.

Formal definition

Initial valueas each of the properties of the shorthand:
Applies topositioned elements
Inheritedno
Percentageslogical-height of containing block
Computed valueas each of the properties of the shorthand:
Animation typea length, percentage or calc();

Formal syntax

inset-block = 
  <'top'>{1,2}  

<top> = 
  auto                 |
  <length-percentage>  |
  <anchor()>           |
  <anchor-size()>      

<length-percentage> = 
  <length>      |
  <percentage>  

<anchor()> = 
  anchor( <anchor-name>?                  &&
  <anchor-side> , <length-percentage>? )  

<anchor-size()> = 
  anchor-size( [ <anchor-name> || <anchor-size> ]? , <length-percentage>? )  

<anchor-name> = 
  <dashed-ident>  

<anchor-side> = 
  inside        |
  outside       |
  top           |
  left          |
  right         |
  bottom        |
  start         |
  end           |
  self-start    |
  self-end      |
  <percentage>  |
  center        

<anchor-size> = 
  width        |
  height       |
  block        |
  inline       |
  self-block   |
  self-inline

Examples

undefined

Setting block start and end offsets

HTML

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

CSS

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

.exampleText {
  writing-mode: vertical-lr;
  position: relative;
  inset-block: 20px 50px;
  background-color: #c8c800;
}

Result

Specifications

See also