This feature is well established and works across many devices and browser versions. It’s been available across browsers since April 2021.
* Some parts of this feature may have varying levels of support.
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.
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;
}
This property is a shorthand for the following CSS properties:
/* <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;
The inset-block property takes the same values as the left property.
| Initial value | as each of the properties of the shorthand:
|
|---|---|
| Applies to | positioned elements |
| Inherited | no |
| Percentages | logical-height of containing block |
| Computed value | as each of the properties of the shorthand:
|
| Animation type | a length, percentage or calc(); |
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
<div> <p class="exampleText">Example text</p> </div>
div {
background-color: yellow;
width: 120px;
height: 120px;
}
.exampleText {
writing-mode: vertical-lr;
position: relative;
inset-block: 20px 50px;
background-color: #c8c800;
}
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Opera | Safari | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | WebView Android | WebView on iOS | |
inset-block |
87 | 87 | 6341–63 | 73 | 14.1 | 87 | 6341–63 | 62 | 14.5 | 14.0 | 87 | 14.5 |
anchor |
125 | 125 | No | 111 | 26 | 125 | No | 83 | 26 | 27.0 | 125 | 26 |
anchor-size |
132 | 132 | No | 117 | 26 | 132 | No | 87 | 26 | No | 132 | 26 |
auto |
87 | 87 | 41 | 73 | 14.1 | 87 | 41 | 62 | 14.5 | 14.0 | 87 | 14.5 |
top, right, bottom, and left
inset
inset-inline
writing-mode, direction, text-orientation
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https://developer.mozilla.org/en-US/docs/Web/CSS/inset-block