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<!doctype html><html lang="en">
<head>
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
<meta content="width=device-width, initial-scale=1, shrink-to-fit=no" name="viewport">
<title>CSS Spatial Layout Module Level 1</title>
<meta content="UD" name="w3c-status">
<link href="https://www.w3.org/StyleSheets/TR/2021/W3C-UD" rel="stylesheet">
<meta content="Bikeshed version 0a54f4e7d, updated Fri Jun 12 15:51:37 2026 -0700" name="generator">
<link href="TBD" rel="canonical">
<meta content="b4bd4159534608714e860fd93f69f5154b320bf0" name="revision">
<meta content="dark light" name="color-scheme">
<link href="https://www.w3.org/StyleSheets/TR/2021/dark.css" media="(prefers-color-scheme: dark)" rel="stylesheet" type="text/css">
<style>/* Boilerplate: style-autolinks */
.css.css, .property.property, .descriptor.descriptor {
color: var(--a-normal-text);
font-size: inherit;
font-family: inherit;
}
.css::before, .property::before, .descriptor::before {
content: "‘";
}
.css::after, .property::after, .descriptor::after {
content: "’";
}
.property, .descriptor {
/* Don't wrap property and descriptor names */
white-space: nowrap;
}
.type { /* CSS value <type> */
font-style: italic;
}
pre .property::before, pre .property::after {
content: "";
}
[data-link-type="property"]::before,
[data-link-type="propdesc"]::before,
[data-link-type="descriptor"]::before,
[data-link-type="value"]::before,
[data-link-type="function"]::before,
[data-link-type="at-rule"]::before,
[data-link-type="selector"]::before,
[data-link-type="maybe"]::before {
content: "‘";
}
[data-link-type="property"]::after,
[data-link-type="propdesc"]::after,
[data-link-type="descriptor"]::after,
[data-link-type="value"]::after,
[data-link-type="function"]::after,
[data-link-type="at-rule"]::after,
[data-link-type="selector"]::after,
[data-link-type="maybe"]::after {
content: "’";
}
[data-link-type].production::before,
[data-link-type].production::after,
.prod [data-link-type]::before,
.prod [data-link-type]::after {
content: "";
}
[data-link-type=element],
[data-link-type=element-attr] {
font-family: Menlo, Consolas, "DejaVu Sans Mono", monospace;
font-size: .9em;
}
[data-link-type=element]::before { content: "<" }
[data-link-type=element]::after { content: ">" }
[data-link-type=biblio] {
white-space: pre;
}
@media (prefers-color-scheme: dark) {
:root {
--selflink-text: black;
--selflink-bg: silver;
--selflink-hover-text: white;
}
}
</style>
<style>/* Boilerplate: style-colors */
/* Any --*-text not paired with a --*-bg is assumed to have a transparent bg */
:root {
color-scheme: light dark;
--text: black;
--bg: white;
--unofficial-watermark: url(https://www.w3.org/StyleSheets/TR/2016/logos/UD-watermark);
--logo-bg: #1a5e9a;
--logo-active-bg: #c00;
--logo-text: white;
--tocnav-normal-text: #707070;
--tocnav-normal-bg: var(--bg);
--tocnav-hover-text: var(--tocnav-normal-text);
--tocnav-hover-bg: #f8f8f8;
--tocnav-active-text: #c00;
--tocnav-active-bg: var(--tocnav-normal-bg);
--tocsidebar-text: var(--text);
--tocsidebar-bg: #f7f8f9;
--tocsidebar-shadow: rgba(0,0,0,.1);
--tocsidebar-heading-text: hsla(203,20%,40%,.7);
--toclink-text: var(--text);
--toclink-underline: #3980b5;
--toclink-visited-text: var(--toclink-text);
--toclink-visited-underline: #054572;
--heading-text: #005a9c;
--hr-text: var(--text);
--algo-border: #def;
--del-text: red;
--del-bg: transparent;
--ins-text: #080;
--ins-bg: transparent;
--a-normal-text: #034575;
--a-normal-underline: #bbb;
--a-visited-text: var(--a-normal-text);
--a-visited-underline: #707070;
--a-hover-bg: rgba(75%, 75%, 75%, .25);
--a-active-text: #c00;
--a-active-underline: #c00;
--blockquote-border: silver;
--blockquote-bg: transparent;
--blockquote-text: currentcolor;
--issue-border: #e05252;
--issue-bg: #fbe9e9;
--issue-text: var(--text);
--issueheading-text: #831616;
--example-border: #e0cb52;
--example-bg: #fcfaee;
--example-text: var(--text);
--exampleheading-text: #574b0f;
--note-border: #52e052;
--note-bg: #e9fbe9;
--note-text: var(--text);
--noteheading-text: hsl(120, 70%, 30%);
--notesummary-underline: silver;
--assertion-border: #aaa;
--assertion-bg: #eee;
--assertion-text: black;
--advisement-border: orange;
--advisement-bg: #fec;
--advisement-text: var(--text);
--advisementheading-text: #b35f00;
--warning-border: red;
--warning-bg: hsla(40,100%,50%,0.95);
--warning-text: var(--text);
--amendment-border: #330099;
--amendment-bg: #F5F0FF;
--amendment-text: var(--text);
--amendmentheading-text: #220066;
--def-border: #8ccbf2;
--def-bg: #def;
--def-text: var(--text);
--defrow-border: #bbd7e9;
--datacell-border: silver;
--indexinfo-text: #707070;
--indextable-hover-text: black;
--indextable-hover-bg: #f7f8f9;
--outdatedspec-bg: rgba(0, 0, 0, .5);
--outdatedspec-text: black;
--outdated-bg: maroon;
--outdated-text: white;
--outdated-shadow: red;
--editedrec-bg: darkorange;
}
@media (prefers-color-scheme: dark) {
:root {
--text: #ddd;
--bg: black;
--unofficial-watermark: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='400' height='400'%3E%3Cg fill='%23100808' transform='translate(200 200) rotate(-45) translate(-200 -200)' stroke='%23100808' stroke-width='3'%3E%3Ctext x='50%25' y='220' style='font: bold 70px sans-serif; text-anchor: middle; letter-spacing: 6px;'%3EUNOFFICIAL%3C/text%3E%3Ctext x='50%25' y='305' style='font: bold 70px sans-serif; text-anchor: middle; letter-spacing: 6px;'%3EDRAFT%3C/text%3E%3C/g%3E%3C/svg%3E");
--logo-bg: #1a5e9a;
--logo-active-bg: #c00;
--logo-text: white;
--tocnav-normal-text: #999;
--tocnav-normal-bg: var(--bg);
--tocnav-hover-text: var(--tocnav-normal-text);
--tocnav-hover-bg: #080808;
--tocnav-active-text: #f44;
--tocnav-active-bg: var(--tocnav-normal-bg);
--tocsidebar-text: var(--text);
--tocsidebar-bg: #080808;
--tocsidebar-shadow: rgba(255,255,255,.1);
--tocsidebar-heading-text: hsla(203,20%,40%,.7);
--toclink-text: var(--text);
--toclink-underline: #6af;
--toclink-visited-text: var(--toclink-text);
--toclink-visited-underline: #054572;
--heading-text: #8af;
--hr-text: var(--text);
--algo-border: #456;
--del-text: #f44;
--del-bg: transparent;
--ins-text: #4a4;
--ins-bg: transparent;
--a-normal-text: #6af;
--a-normal-underline: #555;
--a-visited-text: var(--a-normal-text);
--a-visited-underline: var(--a-normal-underline);
--a-hover-bg: rgba(25%, 25%, 25%, .2);
--a-active-text: #f44;
--a-active-underline: var(--a-active-text);
--borderedblock-bg: rgba(255, 255, 255, .05);
--blockquote-border: silver;
--blockquote-bg: var(--borderedblock-bg);
--blockquote-text: currentcolor;
--issue-border: #e05252;
--issue-bg: var(--borderedblock-bg);
--issue-text: var(--text);
--issueheading-text: hsl(0deg, 70%, 70%);
--example-border: hsl(50deg, 90%, 60%);
--example-bg: var(--borderedblock-bg);
--example-text: var(--text);
--exampleheading-text: hsl(50deg, 70%, 70%);
--note-border: hsl(120deg, 100%, 35%);
--note-bg: var(--borderedblock-bg);
--note-text: var(--text);
--noteheading-text: hsl(120, 70%, 70%);
--notesummary-underline: silver;
--assertion-border: #444;
--assertion-bg: var(--borderedblock-bg);
--assertion-text: var(--text);
--advisement-border: orange;
--advisement-bg: #222218;
--advisement-text: var(--text);
--advisementheading-text: #f84;
--warning-border: red;
--warning-bg: hsla(40,100%,20%,0.95);
--warning-text: var(--text);
--amendment-border: #330099;
--amendment-bg: #080010;
--amendment-text: var(--text);
--amendmentheading-text: #cc00ff;
--def-border: #8ccbf2;
--def-bg: #080818;
--def-text: var(--text);
--defrow-border: #136;
--datacell-border: silver;
--indexinfo-text: #aaa;
--indextable-hover-text: var(--text);
--indextable-hover-bg: #181818;
--outdatedspec-bg: rgba(255, 255, 255, .5);
--outdatedspec-text: black;
--outdated-bg: maroon;
--outdated-text: white;
--outdated-shadow: red;
--editedrec-bg: darkorange;
}
/* In case a transparent-bg image doesn't expect to be on a dark bg,
which is quite common in practice... */
img { background: white; }
}
</style>
<style>/* Boilerplate: style-counters */
body {
counter-reset: example figure issue table;
}
.issue {
counter-increment: issue;
}
.issue:not(.no-marker)::before {
content: "Issue " counter(issue);
}
.example {
counter-increment: example;
}
.example:not(.no-marker)::before {
content: "Example " counter(example);
}
.invalid.example:not(.no-marker)::before,
.illegal.example:not(.no-marker)::before {
content: "Invalid Example " counter(example);
}
figcaption {
counter-increment: figure;
}
figcaption:not(.no-marker)::before {
content: "Figure " counter(figure) " ";
}
figure.table figcaption {
counter-increment: table;
}
figure.table figcaption:not(.no-marker)::before {
content: "Table " counter(table) " ";
}
</style>
<style>/* Boilerplate: style-dfn-panel */
:root {
--dfnpanel-bg: #ddd;
--dfnpanel-text: var(--text);
--dfnpanel-target-bg: #ffc;
--dfnpanel-target-outline: orange;
}
@media (prefers-color-scheme: dark) {
:root {
--dfnpanel-bg: #222;
--dfnpanel-text: var(--text);
--dfnpanel-target-bg: #333;
--dfnpanel-target-outline: silver;
}
}
.dfn-panel {
position: absolute;
z-index: 35;
width: 20em;
width: 300px;
height: auto;
max-height: 500px;
overflow: auto;
padding: 0.5em 0.75em;
font: small Helvetica Neue, sans-serif, Droid Sans Fallback;
background: var(--dfnpanel-bg);
color: var(--dfnpanel-text);
border: outset 0.2em;
white-space: normal; /* in case it's moved into a pre */
}
.dfn-panel:not(.on) { display: none; }
.dfn-panel * { margin: 0; padding: 0; text-indent: 0; }
.dfn-panel > b { display: block; }
.dfn-panel a { color: var(--dfnpanel-text); }
.dfn-panel a:not(:hover) { text-decoration: none !important; border-bottom: none !important; }
.dfn-panel a:focus {
outline: 5px auto Highlight;
outline: 5px auto -webkit-focus-ring-color;
}
.dfn-panel > b + b { margin-top: 0.25em; }
.dfn-panel ul { padding: 0 0 0 1em; list-style: none; }
.dfn-panel li a {
max-width: calc(300px - 1.5em - 1em);
overflow: hidden;
text-overflow: ellipsis;
}
.dfn-panel.activated {
display: inline-block;
position: fixed;
left: 8px;
bottom: 2em;
margin: 0 auto;
max-width: calc(100vw - 1.5em - .4em - .5em);
max-height: 30vh;
transition: left 1s ease-out, bottom 1s ease-out;
}
.dfn-panel .link-item:hover {
text-decoration: underline;
}
.dfn-panel .link-item .copy-icon {
opacity: 0;
}
.dfn-panel .link-item:hover .copy-icon,
.dfn-panel .link-item .copy-icon:focus {
opacity: 1;
}
.dfn-panel .copy-icon {
display: inline-block;
margin-right: 0.5em;
width: 0.85em;
height: 1em;
border-radius: 3px;
background-color: #ccc;
cursor: pointer;
}
.dfn-panel .copy-icon .icon {
width: 100%;
height: 100%;
background-color: #fff;
display: flex;
justify-content: center;
align-items: center;
position: relative;
}
.dfn-panel .copy-icon .icon::before {
content: "";
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
border: 1px solid black;
background-color: #ccc;
opacity: 0.25;
transform: translate(3px, -3px);
}
.dfn-panel .copy-icon:active .icon::before {
opacity: 1;
}
.dfn-paneled[role="button"] { cursor: help; }
.highlighted {
animation: target-fade 3s;
}
@keyframes target-fade {
from {
background-color: var(--dfnpanel-target-bg);
outline: 5px solid var(--dfnpanel-target-outline);
}
to {
color: var(--a-normal-text);
background-color: transparent;
outline: transparent;
}
}
</style>
<style>/* Boilerplate: style-issues */
a[href].issue-return {
float: right;
float: inline-end;
color: var(--issueheading-text);
font-weight: bold;
text-decoration: none;
}
</style>
<style>/* Boilerplate: style-md-lists */
/* This is a weird hack for me not yet following the commonmark spec
regarding paragraph and lists. */
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<body class="h-entry">
<div class="head">
<h1 class="no-ref p-name" id="title">CSS Spatial Layout Module Level 1</h1>
<p id="w3c-state"><a href="https://www.w3.org/standards/types/#UD">Unofficial Proposal Draft</a>,
<time class="dt-updated" datetime="2026-10-27">27 October 2026</time></p>
<details open>
<summary>More details about this document</summary>
<div data-fill-with="spec-metadata">
<dl>
<dt>This version:
<dd><a class="u-url" href="TBD">TBD</a>
<dt>Issue Tracking:
<dd><a href="https://github.com/WebKit/explainers/issues">WebKit Explainers Repository Issues</a>
<dd><a href="#issues-index">Inline In Spec</a>
<dt class="editor">Editors:
<dd class="editor h-card p-author vcard" data-editor-id="66378"><a class="email fn p-name u-email" href="mailto:adarose@apple.com">Ada Rose Cannon</a> (<span class="org p-org">Apple</span>)
<dd class="editor h-card p-author vcard" data-editor-id="35400"><a class="fn p-name u-url url" href="http://fantasai.inkedblade.net/contact">Elika J. Etemad / fantasai</a> (<span class="org p-org">Apple</span>)
<dt>Suggest an Edit for this Spec:
<dd><a href="https://github.com/w3c/csswg-drafts/blob/main/css-spatial-3/Overview.bs">GitHub Editor</a>
</dl>
</div>
</details>
<div data-fill-with="warning"></div>
<p class="copyright" data-fill-with="copyright">Copyright © 2026 Apple.
</p>
<hr title="Separator for header">
</div>
<div class="p-summary" data-fill-with="abstract">
<h2 class="heading no-num no-ref no-toc settled" id="abstract"><span class="content">Abstract</span></h2>
<p>This module introduces three-dimensional layout to the CSS rendering model.</p>
<a href="https://www.w3.org/TR/CSS/">CSS</a> is a language for describing the rendering of structured documents
(such as HTML and XML)
on screen, on paper, etc.
</div>
<h2 class="heading no-num no-ref no-toc settled" id="sotd"><span class="content">Status of this document</span></h2>
<div data-fill-with="status">
<p>This is an unofficial draft produced as an extension proposal for CSS.
If accepted, it would most likely become a work item of the <a href="https://www.w3.org/Style/CSS/">W3C CSS Working Group</a>.
</p>
</div>
<div data-fill-with="at-risk"></div>
<nav data-fill-with="table-of-contents" id="toc">
<h2 class="no-num no-ref no-toc" id="contents">Table of Contents</h2>
<ol class="toc">
<li>
<a href="#intro"><span class="secno">1</span> <span class="content">
Introduction</span></a>
<ol class="toc">
<li><a href="#values"><span class="secno">1.1</span> <span class="content">
Value Definitions</span></a>
</ol>
<li>
<a href="#spatial-contexts"><span class="secno">2</span> <span class="content">
Establishing Spatial Contexts</span></a>
<ol class="toc">
<li><a href="#portals"><span class="secno">2.1</span> <span class="content">
Establishing Spatial Contexts and Portals: the <span class="property">spatial</span> property</span></a>
<li>
<a href="#spatial-layout-model"><span class="secno">2.2</span> <span class="content">
Spatial Contexts and the Spatial Layout Model</span></a>
<ol class="toc">
<li><a href="#spatial-context-front"><span class="secno">2.2.1</span> <span class="content">
The Front Spatial Context</span></a>
<li><a href="#spatial-context-back"><span class="secno">2.2.2</span> <span class="content">
The Back Spatial Context</span></a>
<li><a href="#spatial-context-full"><span class="secno">2.2.3</span> <span class="content">
Full Portals: Connecting the Front and Back Spatial Contexts</span></a>
</ol>
<li>
<a href="#portal-config"><span class="secno">2.3</span> <span class="content">
Configuring the Back Spatial Context</span></a>
<ol class="toc">
<li>
<a href="#stage-volume"><span class="secno">2.3.1</span> <span class="content">
Defining Stage: the <span class="property">portal-stage</span> property</span></a>
<ol class="toc">
<li><a href="#portal-stage-auto-volume"><span class="secno">2.3.1.1</span> <span class="content">
Calculating an Automatic Containing Volume</span></a>
</ol>
<li><a href="#stage-transform"><span class="secno">2.3.2</span> <span class="content">
Transforming the Stage: the <span class="property">portal-transform</span> property</span></a>
<li><a href="#stage-interactivity"><span class="secno">2.3.3</span> <span class="content">
Interacting with the Stage: the <span class="property">portal-action</span> property</span></a>
</ol>
<li>
<a href="#front-limits"><span class="secno">2.4</span> <span class="content">
Front Limits: how far content can be raised on the page</span></a>
<ol class="toc">
<li><a href="#front-limit-property"><span class="secno">2.4.1</span> <span class="content">
Controlling the Front Limit: the <span class="property">front-limit</span> property</span></a>
<li><a href="#front-limit-query"><span class="secno">2.4.2</span> <span class="content">
Querying the Front Limit: the <span class="property">front-limit</span> media query</span></a>
</ol>
<li><a href="#spatial-colors"><span class="secno">2.5</span> <span class="content">
Color Compositing in Spatial Contexts</span></a>
</ol>
<li>
<a href="#position-spatial"><span class="secno">3</span> <span class="content">
Spatial Positioning</span></a>
<ol class="toc">
<li>
<a href="#position-spatial-relative"><span class="secno">3.1</span> <span class="content">
Relative Spatial Positioning</span></a>
<ol class="toc">
<li><a href="#position-spatial-relative-clamping"><span class="secno">3.1.1</span> <span class="content">
Clamping Relative Spatial Positioning to the Front Limit</span></a>
</ol>
<li><a href="#position-spatial-absolute"><span class="secno">3.2</span> <span class="content">
Absolute Spatial Positioning: the <span class="css">spatial-absolute</span> keyword for <span class="property">position</span></span></a>
<li>
<a href="#front-back"><span class="secno">3.3</span> <span class="content">
Z-axis Insets: the <span class="property">inset-front</span> and <span class="property">inset-back</span> properties</span></a>
<ol class="toc">
<li><a href="#inset-aliasing"><span class="secno">3.3.1</span> <span class="content">
Inset Aliases: the <span class="property">inset-top</span>, <span class="property">inset-right</span>, <span class="property">inset-bottom</span>, and <span class="property">inset-left</span> properties</span></a>
<li><a href="#inset-shorthand"><span class="secno">3.3.2</span> <span class="content">
Inset Shorthand: the <span class="css">/ <<span class="property">inset-back</span>> <<span class="property">inset-front</span>>?</span> extension to <span class="property">inset</span></span></a>
</ol>
<li>
<a href="#spatial-anchor-positioning"><span class="secno">3.4</span> <span class="content">
Anchor-based Positioning</span></a>
<ol class="toc">
<li><a href="#spatial-anchor-coordinates"><span class="secno">3.4.1</span> <span class="content">
Anchor-based Coordinates: the <span class="property">position-context</span> property</span></a>
<li><a href="#position-area-3d"><span class="secno">3.4.2</span> <span class="content">
Extensions to <span class="property">position-area</span>: 3-dimensional areas</span></a>
<li><a href="#position-area-origin"><span class="secno">3.4.3</span> <span class="content">
Extensions to <span class="property">position-area</span>: the <span class="css">origin</span> area</span></a>
<li><a href="#inset-anchor-3d"><span class="secno">3.4.4</span> <span class="content">
Extensions to <span class="css">anchor()</span> and <span class="css">anchor-size()</span></span></a>
<li><a href="#z-alignment"><span class="secno">3.4.5</span> <span class="content">
Extensions to Box Alignment: the <span class="property">z-align-self</span> and <span class="property">z-align-items</span> properties</span></a>
<li><a href="#origin-anchoring"><span class="secno">3.4.6</span> <span class="content">
Extensions to Anchor Alignment: the <span class="css">anchor-origin</span> value</span></a>
<li><a href="#object-origin"><span class="secno">3.4.7</span> <span class="content">
Defining the Origin</span></a>
</ol>
</ol>
<li><a href="#spatial-transforms"><span class="secno">4</span> <span class="content">
Spatial Transforms</span></a>
<li><a href="#interactions-with-spatial-content"><span class="secno">5</span> <span class="content">
Interactions with Spatial Content</span></a>
<li>
<a href="#environment-maps"><span class="secno">6</span> <span class="content">
Environment Maps</span></a>
<ol class="toc">
<li>
<a href="#environment-map-definition"><span class="secno">6.1</span> <span class="content">
Defining Environment Maps: the <span class="css">@environment-map</span> rule</span></a>
<ol class="toc">
<li><a href="#environment-map-names"><span class="secno">6.1.1</span> <span class="content">
Naming an Environment Map: the <span class="property">name</span> descriptor</span></a>
<li>
<a href="#environment-map-formats"><span class="secno">6.1.2</span> <span class="content">
Environment Map Formats: the <span class="property">format</span> descriptor</span></a>
<ol class="toc">
<li><a href="#cube-mapping"><span class="secno">6.1.2.1</span> <span class="content">
Mapping Images Onto a Cube</span></a>
</ol>
<li><a href="#environment-map-src"><span class="secno">6.1.3</span> <span class="content">
Environment Map Images: the <span class="property">src</span> descriptor</span></a>
</ol>
<li>
<a href="#environment-map-references"><span class="secno">6.2</span> <span class="content">
Applying Environment Maps</span></a>
<ol class="toc">
<li><a href="#environment-map-property"><span class="secno">6.2.1</span> <span class="content">
Referencing an Environment Map: the <span class="property">environment-map</span> property</span></a>
<li><a href="#environment-map-intensity"><span class="secno">6.2.2</span> <span class="content">
Brightening and Dimming the Environment: the <span class="property">environment-intensity</span> property</span></a>
<li><a href="#environment-map-rotate"><span class="secno">6.2.3</span> <span class="content">
Rotating the Environment: the <span class="property">environment-rotate</span> property</span></a>
<li><a href="#environment-shorthand"><span class="secno">6.2.4</span> <span class="content">
Declaring the Environment: the <span class="property">environment</span> shorthand</span></a>
</ol>
</ol>
<li><a href="#ua-stylesheet"><span class="secno"></span> <span class="content">
Appendix A: Default UA Stylesheet</span></a>
<li>
<a href="#w3c-conformance"><span class="secno"></span> <span class="content">
Conformance</span></a>
<ol class="toc">
<li><a href="#w3c-conventions"><span class="secno"></span> <span class="content">
Document conventions</span></a>
<li><a href="#w3c-conformance-classes"><span class="secno"></span> <span class="content">
Conformance classes</span></a>
<li>
<a href="#w3c-partial"><span class="secno"></span> <span class="content">
Partial implementations</span></a>
<ol class="toc">
<li><a href="#w3c-conform-future-proofing"><span class="secno"></span> <span class="content">
Implementations of Unstable and Proprietary Features</span></a>
</ol>
<li><a href="#w3c-testing"><span class="secno"></span> <span class="content">
Non-experimental implementations</span></a>
</ol>
<li>
<a href="#index"><span class="secno"></span> <span class="content">Index</span></a>
<ol class="toc">
<li><a href="#index-defined-here"><span class="secno"></span> <span class="content">Terms defined by this specification</span></a>
<li><a href="#index-defined-elsewhere"><span class="secno"></span> <span class="content">Terms defined by reference</span></a>
</ol>
<li>
<a href="#references"><span class="secno"></span> <span class="content">References</span></a>
<ol class="toc">
<li><a href="#normative"><span class="secno"></span> <span class="content">Normative References</span></a>
<li><a href="#informative"><span class="secno"></span> <span class="content">Non-Normative References</span></a>
</ol>
<li>
<a href="#property-index"><span class="secno"></span> <span class="content">Property Index</span></a>
<ol class="toc">
<li><a href="#environment-map-descriptor-table"><span class="secno"></span> <span class="content"><span>@environment-map</span> Descriptors</span></a>
<li><a href="#media-descriptor-table"><span class="secno"></span> <span class="content"><span>@media</span> Descriptors</span></a>
</ol>
<li><a href="#issues-index"><span class="secno"></span> <span class="content">Issues Index</span></a>
</ol>
</nav>
<main>
<h2 class="heading settled" data-level="1" id="intro"><span class="secno">1. </span><span class="content">
Introduction</span><a class="self-link" href="#intro"></a></h2>
<p><em>This section is not normative.</em></p>
<p>This module introduces spatial (3-dimensional) layout to CSS,
creating <a data-link-type="dfn" href="#spatial-context" id="ref-for-spatial-context">spatial contexts</a> and
extending <a data-link-type="dfn" href="https://www.w3.org/TR/CSS2/visuren.html#x34" id="ref-for-x34">relative</a> and <a data-link-type="dfn" href="https://drafts.csswg.org/css-position-3/#absolute-position" id="ref-for-absolute-position">absolute</a> positioning
to handle the <dfn class="dfn-paneled" data-dfn-type="dfn" data-lt="z-axis|z axis" data-noexport id="z-axis">z-axis</dfn> (perpendicular to the canvas).</p>
<p class="note" role="note"><span class="marker">Note:</span> The <a class="css property" data-link-type="property" href="https://drafts.csswg.org/css2/#propdef-z-index" id="ref-for-propdef-z-index">z-index</a> property is unrelated to <a data-link-type="dfn" href="#spatial-positioning" id="ref-for-spatial-positioning">spatial positioning</a>,
it merely controls the stacking order at a given <a data-link-type="dfn" href="#z-axis" id="ref-for-z-axis">z-axis</a> position.</p>
<h3 class="heading settled" data-level="1.1" id="values"><span class="secno">1.1. </span><span class="content">
Value Definitions</span><a class="self-link" href="#values"></a></h3>
<p>This specification follows the <a href="https://www.w3.org/TR/CSS2/about.html#property-defs">CSS property definition conventions</a> from <a data-link-type="biblio" href="#biblio-css2" title="Cascading Style Sheets Level 2 Revision 1 (CSS 2.1) Specification">[CSS2]</a>
using the <a href="https://www.w3.org/TR/css-values-3/#value-defs">value definition syntax</a> from <a data-link-type="biblio" href="#biblio-css-values-3" title="CSS Values and Units Module Level 3">[CSS-VALUES-3]</a>.
Value types not defined in this specification are defined in CSS Values & Units <a data-link-type="biblio" href="#biblio-css-values-3" title="CSS Values and Units Module Level 3">[CSS-VALUES-3]</a>.
Combination with other CSS modules may expand the definitions of these value types.</p>
<p>In addition to the property-specific values listed in their definitions,
all properties defined in this specification
also accept the <a data-link-type="dfn" href="https://drafts.csswg.org/css-values-4/#css-wide-keywords" id="ref-for-css-wide-keywords">CSS-wide keywords</a> as their property value.
For readability they have not been repeated explicitly.</p>
<h2 class="heading settled" data-level="2" id="spatial-contexts"><span class="secno">2. </span><span class="content">
Establishing Spatial Contexts</span><a class="self-link" href="#spatial-contexts"></a></h2>
<h3 class="heading settled" data-level="2.1" id="portals"><span class="secno">2.1. </span><span class="content">
Establishing Spatial Contexts and Portals: the <a class="css property" data-link-type="property" href="#propdef-spatial" id="ref-for-propdef-spatial">spatial</a> property</span><a class="self-link" href="#portals"></a></h3>
<table class="def propdef" data-link-for-hint="spatial">
<tbody>
<tr>
<th>Name:
<td><dfn class="css dfn-paneled" data-dfn-type="property" data-export id="propdef-spatial">spatial</dfn>
<tr class="value">
<th><a href="https://www.w3.org/TR/css-values/#value-defs">Value:</a>
<td class="prod">none <a data-link-type="grammar" href="https://drafts.csswg.org/css-values-4/#comb-one" id="ref-for-comb-one">|</a> page <span id="ref-for-comb-one①">|</span> portal
<tr>
<th><a href="https://www.w3.org/TR/css-cascade/#initial-values">Initial:</a>
<td>none
<tr>
<th><a href="https://www.w3.org/TR/css-cascade/#applies-to">Applies to:</a>
<td>all elements except <a data-link-type="dfn" href="https://drafts.csswg.org/css-display-4/#internal-table-element" id="ref-for-internal-table-element">internal table elements</a>, <a data-link-type="dfn" href="https://drafts.csswg.org/css-display-4/#internal-ruby-element" id="ref-for-internal-ruby-element">internal ruby elements</a>, and <a data-link-type="dfn" href="https://drafts.csswg.org/css-display-4/#inline-box" id="ref-for-inline-box">inline boxes</a>
<tr>
<th><a href="https://www.w3.org/TR/css-cascade/#inherited-property">Inherited:</a>
<td>no
<tr>
<th><a href="https://www.w3.org/TR/css-values/#percentages">Percentages:</a>
<td>n/a
<tr>
<th><a href="https://www.w3.org/TR/css-cascade/#computed">Computed value:</a>
<td>as specified
<tr>
<th><a href="https://www.w3.org/TR/cssom/#serializing-css-values">Canonical order:</a>
<td>per grammar
<tr>
<th><a href="https://www.w3.org/TR/web-animations/#animation-type">Animation type:</a>
<td>discrete
</table>
<p>The <a class="css property" data-link-type="property" href="#propdef-spatial" id="ref-for-propdef-spatial①">spatial</a> property establishes a <dfn class="dfn-paneled" data-dfn-type="dfn" data-noexport id="spatial-container">spatial container</dfn>,
generating one or more <a data-link-type="dfn" href="#spatial-context" id="ref-for-spatial-context①">spatial contexts</a>
allowing 3-dimensional layout within the context.</p>
<p class="issue" id="issue-475b208d"><a class="self-link" href="#issue-475b208d"></a> This property was previously named <span class="css">portal</span>,
since it would establish a shared spatial context