[css-pseudo-4] Rename part-like to element-backed and clean up prose

Author: fantasai

css-pseudo-4/Overview.bs

@@ -1368,6 +1368,9 @@ Tree-Abiding Pseudo-elements</h2>
   They <a lt="inheritance">inherit</a> any inheritable properties from their <a>originating element</a>;
   non-inheritable properties take their <a>initial values</a> as usual.
   [[CSS-CASCADE-4]]
+  A subset of these are the <dfn>fully styleable pseudo-elements</dfn>;
+  all properties that apply to a real element
+  also apply to a [=fully styleable pseudo-element=].
 
   <wpt>
     parsing/tree-abiding-pseudo-elements.html
@@ -1398,7 +1401,7 @@ Generated Content Pseudo-elements: ''::before'' and ''::after''</h3>
   </wpt>
 
   Both ''::before'' and ''::after''
-  are [=part-like pseudo-elements=];
+  are [=fully styleable pseudo-elements=]:
   there is no restriction on what properties apply to them.
 
   <div class="example">
@@ -1578,51 +1581,47 @@ Placeholder Input: the ''::placeholder'' pseudo-element</h3>
   It's not clear how this should work, but it may be worth doing.
   See <a href="https://github.com/w3c/csswg-drafts/issues/2517">Issue 2417</a>.
 
-<h2 id=partlike>
-Part-Like Pseudo-Elements</h2>
+<h2 id="element-like" oldids=part-like>
+Element-backed Pseudo-Elements</h2>
 
-  A subset of [=tree-abiding pseudo-elements=],
-  the <dfn export lt="part-like|part-like pseudo-element">part-like pseudo-elements</dfn>,
-  have slightly stronger requirements:
-  they act as if they have a well-defined location in the document tree.
-  This enables them to interact with some other platform features
+  The <dfn export lt="element-backed|element-backed pseudo-element">element-backed pseudo-elements</dfn>,
+  interact with most CSS and other platform features
   as if they were real elements
-  (and, in fact, they often <em>are</em> real elements,
-  such as in the case of ''::part()'',
-  which simply aren't accessible in the current tree).
-
-  [=Part-like pseudo-elements=] inherit from their [=originating element=] by default,
-  like a standard [=tree-abiding pseudo-element=],
-  but can declare that they inherit from another element instead
-  (possibly not accessible).
+  (and, in fact, often <em>are</em> real elements
+  that are not otherwise selectable).
+
+  Unless otherwise specified,
+  they are fully styleable
+  and inherit from their [=originating element=],
+  just like standard [=tree-abiding pseudo-elements=];
+  but they can be defined to inherit from another element instead.
   (For example, ''::part()'' inherits from
   the parent of the element it represents in the shadow tree.)
 
-  All pseudo-classes and pseudo-elements
-  are syntactically allowed after a [=part-like pseudo-element=],
-  such as ''x-button::part(label):hover''
-  or ''x-button::part(label)::before'',
+  All [=pseudo-classes=] and [=pseudo-elements=]
+  are syntactically allowed after an [=element-backed pseudo-element=]
+  (such as ''x-button::part(label):hover''
+  or ''x-button::part(label)::before''),
+  just as if the pseudo-element were a [=type selector=];
   but some are disallowed from matching:
 
   * The [=structural pseudo-classes=],
     '':has()'' pseudo-class,
     '':scope'' pseudo-class,
     and '':host''/'':host()''/'':host-context()'' pseudo-classes
     never match.
-  * ''::part()'' never matches. (Other [=part-like pseudo-elements=] can, however.)
+  * ''::part()'' never matches. (Other [=element-backed pseudo-elements=] can, however.)
 
-  A [=part-like pseudo-element=] can define itself as representing a real element
-  (possibly not accessible in the current tree).
-  If it does so, all pseudo-classes and pseudo-elements match according to that element,
-  if not disallowed by the previous restrictions.
+  An [=element-backed pseudo-element=] can define itself as representing a real element
+  (possibly one not accessible in the current tree).
+  If it does so,
+  all pseudo-classes and pseudo-elements not otherwise disallowed (see above)
+  match as they would on that real element.
   If it does not do so,
-  it must define which pseudo-classes it matches and when
-  (besides the pseudo-classes defined to work on all pseudo-elements,
-  or all [=tree-abiding pseudo-elements=]).
-
-  Unless otherwise specified,
-  any CSS property that applies to elements
-  applies to [=part-like pseudo-elements=].
+  it must define which pseudo-classes it matches and when;
+  however, unless otherwise specified,
+  any pseudo-classes allowed on [=tree-abiding pseudo-elements=]
+  are always allowed on [=element-backed pseudo-elements=].
 
 
 <h3 id="file-selector-button-pseudo">
@@ -1632,7 +1631,7 @@ File Selector Button: the ''::file-selector-button'' pseudo-element</h3>
   targets the ''&lt;button>''
   inside an ''&lt;input>'' element with <code>type=file</code>,
   if the UA renders such a button.
-  It is a [=part-like pseudo-element=].
+  It is an [=element-backed pseudo-element=].
 
   <wpt>
     file-selector-button-001.html
@@ -1659,7 +1658,7 @@ Expandable contents of details element: the ''::details-content'' pseudo-element
   The <dfn>::details-content</dfn> pseudo-element targets
   the additional information in a a <{details}> element
   that can be expanded or collapsed.
-  It is a [=part-like pseudo-element=].
+  It is an [=element-backed pseudo-element=].
 
   <wpt title="details element">
 
@@ -1689,7 +1688,7 @@ Styling form control pickers: the ''::picker()'' pseudo-element</h3>
 
   The <dfn>::picker()</dfn> pseudo-element targets the popup picker of form
   control elements which have popup pickers, such as the <{select}> element. It
-  is a [=part-like pseudo-element=].
+  is an [=element-backed pseudo-element=].
 
   <pre class=prod>
     ::picker() = ::picker( <<ident>>+ )
@@ -1704,7 +1703,7 @@ Styling form control pickers: the ''::picker()'' pseudo-element</h3>
   <a>originating element</a>. For example, the <a>unique picker name</a> for
   the <{select}> element is "select".
 
-  Since it is a [=part-like pseudo-element=], There is no restriction on which
+  Since it is an [=element-backed pseudo-element=], There is no restriction on which
   properties apply to the ''::picker()'' pseudo-element.
 
   In order for the ''::picker()'' pseudo-element to be rendered, it and its
@@ -1924,16 +1923,15 @@ Changes</h2>
 
   <ul>
     <!-- to 30 Aug 2024 -->
-    <li>Added ::details-content pseudo-element (<a href="https://github.com/w3c/csswg-drafts/pull/10379">Issue 10379</a>) </li>
-    <li>Defined "part-like pseudo-element" (<a href="https://github.com/w3c/csswg-drafts/pull/10199">Issue 10199</a>, <a href="https://github.com/w3c/csswg-drafts/issues/10083">Issue 10083</a>) </li>
+    <li>Defined [=element-backed pseudo-element=].
+      (<a href="https://github.com/w3c/csswg-drafts/pull/10199">Issue 10199</a>, <a href="https://github.com/w3c/csswg-drafts/issues/10083">Issue 10083</a>)
+    <li>Added ''::details-content'' pseudo-element
+      (<a href="https://github.com/w3c/csswg-drafts/pull/10379">Issue 10379</a>)
     <li>Clarified that the inherited value of 'color' is ''currentColor'', not the [=initial value=].
-    </li>
     <li>Clarified that a custom property may be defined and/or used inside a highlight pseudo-element.
-    </li>
     <li>Defined the behavior when custom property values are not found in the
         highlight cascade; they are taken from the root.
         (<a href="https://github.com/w3c/csswg-drafts/issues/6641">Issue 6641</a>)
-    </li>
   </ul>