anchor-name

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

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

The anchor-name CSS property enables defining an element as an anchor element by giving it one or more identifying anchor names. Each name can then be set as the value of a positioned element's position-anchor property to associate it with the anchor.

Syntax

css

/* Single values */
anchor-name: none;
anchor-name: --name;

/* Multiple values */
anchor-name: --name, --another-name;

/* Global values */
anchor-name: inherit;
anchor-name: initial;
anchor-name: revert;
anchor-name: revert-layer;
anchor-name: unset;

Values

none: The default value. Setting anchor-name: none on an element means that it is not defined as an anchor element. If the element was previously defined as an anchor and associated with a positioned element, setting anchor-name: none disassociates the two.
<dashed-ident>: One or more comma-separated arbitrary custom identifiers defining the name or names of the anchor, which can then be referenced in a position-anchor property.

Description

To position an element relative to an anchor element, the positioned element requires three features: an association, a position, and a location. The anchor-name and position-anchor properties provide the association.

The anchor element accepts one or more <dashed-ident> anchor names set on it via the anchor-name property. When one of those names is then set as the value of the position-anchor property of an element that has its position set to absolute or fixed, the two elements are associated. The two elements become tethered by setting a location on the associated element relative to the anchor, making it an "anchor-positioned" element.

If multiple anchor elements have the same anchor name set on them, and that name is referenced by the position-anchor property value of a positioned element, that positioned element will be associated with the last anchor element with that anchor name in the source order.

Anchor positioning changes the containing block of anchor-positioned elements, making its position relative to its anchor rather than to the nearest positioned ancestor element.

To tether and place a positioned element in a specific location relative to an anchor element, an anchor positioning feature is needed, such as the anchor() function (set within an inset property's value) or the inset-area property.

You cannot associate a positioned element with an anchor element if the anchor is hidden, such as with display: none or visibility: hidden, or if the anchor is part of the skipped contents of another element due to it having content-visibility: hidden set on it.

The anchor-name property is supported on all elements that generate a principal box. This means that pseudo-elements, including generated content created using ::before and ::after, and UI features like the range input thumb (::-webkit-slider-thumb) can be anchor elements. Pseudo elements are implicitly anchored to the same element as the pseudo-element's originating element, unless otherwise specified.

For more information on anchor features and usage, see the CSS anchor positioning module landing page and the Using CSS anchor positioning guide.

Formal definition

Initial value	`none`
Applies to	All elements that generate a principal box
Inherited	no
Computed value	as specified
Animation type	discrete

Formal syntax

anchor-name = 
  none             |
  <dashed-ident>#

Examples

Basic usage

This example tethers a positioned element to an anchor, positioning the element to the right of the anchor.

HTML

We specify two <div> elements; an anchor element with a class of anchor and a positioned element with a class of infobox.

We also include some filler text around the two <div>s to make the <body> taller so that it will scroll.

html

<p>
  Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor
  incididunt ut labore et dolore magna aliqua. Dui nunc mattis enim ut tellus
  elementum sagittis vitae et.
</p>

<div class="anchor">⚓︎</div>

<div class="infobox">
  <p>This is an information box.</p>
</div>

<p>
  Nisi quis eleifend quam adipiscing vitae proin sagittis nisl rhoncus. In arcu
  cursus euismod quis viverra nibh cras pulvinar. Vulputate ut pharetra sit amet
  aliquam.
</p>

<p>
  Malesuada nunc vel risus commodo viverra maecenas accumsan lacus. Vel elit
  scelerisque mauris pellentesque pulvinar pellentesque habitant morbi
  tristique. Porta lorem mollis aliquam ut porttitor. Turpis cursus in hac
  habitasse platea dictumst quisque. Dolor sit amet consectetur adipiscing elit.
  Ornare lectus sit amet est placerat. Nulla aliquet porttitor lacus luctus
  accumsan.
</p>

CSS

We first declare the anchor <div> as an anchor element by setting an anchor name on it via the anchor-name property:

body {
  width: 50%;
  margin: 0 auto;
}

.anchor {
  font-size: 1.8rem;
  color: white;
  text-shadow: 1px 1px 1px black;
  background-color: hsl(240 100% 75%);
  width: fit-content;
  border-radius: 10px;
  border: 1px solid black;
  padding: 3px;
}

css

.anchor {
  anchor-name: --myAnchor;
}

We associate the second <div> with the anchor element by setting its anchor name as the value of the positioned element's position-anchor property. We then set the positioned element's:

position property to fixed, converting it to an anchor-positioned element so it can be positioned relative to the anchor's position on the page.
left and top properties to anchor() functions with values of right and top respectively. This positions the infobox's left edge flush to the right edge of its anchor, and its top edge relative to the top edge of its anchor.
margin-left to 10px, creating space between the anchor positioned element and its anchor.

.infobox {
  color: darkblue;
  background-color: azure;
  border: 1px solid #ddd;
  padding: 10px;
  border-radius: 10px;
  font-size: 1rem;
}

css

.infobox {
  position-anchor: --myAnchor;
  position: fixed;
  left: anchor(right);
  top: anchor(top);
  margin-left: 10px;
}

Result

Scroll the page to see how the infobox is positioned relative to the anchor. As the anchor scrolls upwards, the positioned element moves along with it.

Multiple positioned elements

This example demonstrates how you can associate multiple positioned elements with one anchor.

HTML

The HTML is the same as for the previous example, except this time we have multiple positioned element <div>s with different ids to identify them.

html

<p>
  Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor
  incididunt ut labore et dolore magna aliqua. Dui nunc mattis enim ut tellus
  elementum sagittis vitae et.
</p>

<div class="anchor">⚓︎</div>

<div class="infobox" id="infobox1">
  <p>This is an information box.</p>
</div>

<div class="infobox" id="infobox2">
  <p>This is another information box.</p>
</div>

<p>
  Nisi quis eleifend quam adipiscing vitae proin sagittis nisl rhoncus. In arcu
  cursus euismod quis viverra nibh cras pulvinar. Vulputate ut pharetra sit amet
  aliquam.
</p>

<p>
  Malesuada nunc vel risus commodo viverra maecenas accumsan lacus. Vel elit
  scelerisque mauris pellentesque pulvinar pellentesque habitant morbi
  tristique. Porta lorem mollis aliquam ut porttitor. Turpis cursus in hac
  habitasse platea dictumst quisque. Dolor sit amet consectetur adipiscing elit.
  Ornare lectus sit amet est placerat. Nulla aliquet porttitor lacus luctus
  accumsan.
</p>

CSS

We declare the anchor <div> as an anchor element using the anchor-name property, giving it an anchor name as before.

body {
  width: 50%;
  margin: 0 auto;
}

.anchor {
  font-size: 1.8rem;
  color: white;
  text-shadow: 1px 1px 1px black;
  background-color: hsl(240 100% 75%);
  width: fit-content;
  border-radius: 10px;
  border: 1px solid black;
  padding: 3px;
}

css

.anchor {
  anchor-name: --myAnchor;
}

Each of the two positioned elements are associated with the anchor element by setting its anchor name as the positioned element's position-anchor property value. Both are also given fixed positioning, making them anchor positioned elements. The positioned elements are then positioned in different places relative to the anchor using a combination of inset properties as seen above and align-self / justify-self properties with a value of anchor-center, centrally aligning the infobox to the center of the anchor in the inline/block directions respectively.

.infobox {
  color: darkblue;
  background-color: azure;
  border: 1px solid #ddd;
  padding: 10px;
  border-radius: 10px;
  font-size: 1rem;
}

css

.infobox {
  position-anchor: --myAnchor;
  position: fixed;
}

#infobox1 {
  left: anchor(right);
  align-self: anchor-center;
  margin-left: 10px;
}

#infobox2 {
  bottom: anchor(top);
  justify-self: anchor-center;
  margin-bottom: 15px;
}

Result

Scroll the page to see how both of the infoboxes are tethered to the anchor.

Multiple anchor names

This example demonstrates how an anchor element can have more than one anchor name.

HTML

The HTML is the same as for the previous example.

<p>
  Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor
  incididunt ut labore et dolore magna aliqua. Dui nunc mattis enim ut tellus
  elementum sagittis vitae et.
</p>

<div class="anchor">⚓︎</div>

<div class="infobox" id="infobox1">
  <p>This is an information box.</p>
</div>

<div class="infobox" id="infobox2">
  <p>This is another information box.</p>
</div>

<p>
  Nisi quis eleifend quam adipiscing vitae proin sagittis nisl rhoncus. In arcu
  cursus euismod quis viverra nibh cras pulvinar. Vulputate ut pharetra sit amet
  aliquam.
</p>

<p>
  Malesuada nunc vel risus commodo viverra maecenas accumsan lacus. Vel elit
  scelerisque mauris pellentesque pulvinar pellentesque habitant morbi
  tristique. Porta lorem mollis aliquam ut porttitor. Turpis cursus in hac
  habitasse platea dictumst quisque. Dolor sit amet consectetur adipiscing elit.
  Ornare lectus sit amet est placerat. Nulla aliquet porttitor lacus luctus
  accumsan.
</p>

CSS

The CSS is the same as the previous example too, except we include two comma-separated names in the target's anchor-name property value and each positioned element has a different value for position-anchor.

body {
  width: 50%;
  margin: 0 auto;
}

.anchor {
  font-size: 1.8rem;
  color: white;
  text-shadow: 1px 1px 1px black;
  background-color: hsl(240 100% 75%);
  width: fit-content;
  border-radius: 10px;
  border: 1px solid black;
  padding: 3px;
}

.infobox {
  color: darkblue;
  background-color: azure;
  border: 1px solid #ddd;
  padding: 10px;
  border-radius: 10px;
  font-size: 1rem;
}

css

.anchor {
  anchor-name: --anchor1, --anchor2;
}

.infobox {
  position: fixed;
}

#infobox1 {
  position-anchor: --anchor1;
  left: anchor(right);
  align-self: anchor-center;
  margin-left: 10px;
}

#infobox2 {
  position-anchor: --anchor2;
  bottom: anchor(top);
  justify-self: anchor-center;
  margin-bottom: 15px;
}

Result

Scroll the page to see how both of the infoboxes are tethered to the anchor.

Specifications

Specification
CSS Anchor Positioning # name

Browser compatibility

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