[css-pseudo-4] Add ::target-text pseudo-element per WG resolution.

Author: fantasai

css-pseudo-4/Overview.bs

@@ -438,7 +438,7 @@ Styling the ''::first-letter'' Pseudo-element</h4>
 Highlight Pseudo-elements</h2>
 
 <h3 id="highlight-selectors">
-Selecting Highlighted Content: the ''::selection'',  ''::inactive-selection'', ''::spelling-error'', and ''::grammar-error'' pseudo-elements</h3>
+Selecting Highlighted Content: the ''::selection'',  ''::inactive-selection'', ''::target-text'', ''::spelling-error'', and ''::grammar-error'' pseudo-elements</h3>
 
   The <dfn export lt="highlight pseudo-element">highlight pseudo-elements</dfn>
   represent portions of a document that have been given a particular status
@@ -467,6 +467,16 @@ Selecting Highlighted Content: the ''::selection'',  ''::inactive-selection'', '
       whereas ''::inactive-selection'' applies to inactive selections
       (e.g. when the document window is inactive and therefore not receiving events).
 
+    <dt><dfn>::target-text</dfn>
+    <dd>
+      The ''::target-text'' pseudo-element represents text
+      directly targetted by the document URL’s [=URL/fragment=], if any.
+
+      Note: When a [=URL fragment=] targets an element,
+      the '':target'' pseudo-element can be used to select it,
+      but ''::target-text'' does not match anything.
+      It only matches text that is itself targetted by the [[=URL/fragment=]].
+
     <dt><dfn>::spelling-error</dfn>
     <dd>
       The ''::spelling-error'' pseudo-element represents
@@ -547,11 +557,16 @@ Styling Highlights</h3>
   Note: Historically (and at the time of writing)
   only 'color' and 'background-color' have been interoperably supported.
 
+<h3 id=highlight-ua-styles>
+Default UA Styles</h3>
+
   The following addition is made to the default UA stylesheet:
   <pre><code class="lang-css">
     /* Represent default spelling/grammar error styling in an adjustable way */
     :root::spelling-error { text-decoration-line: spelling-error; }
     :root::grammar-error  { text-decoration-line: grammar-error; }
+    /* Highlight targetted text */
+    :root::target-text    { color: MarkText; background: Mark; }
   </code></pre>
 
 <h3 id=highlight-bounds>
@@ -689,6 +704,7 @@ Backgrounds</h4>
   (i.e. just before step 8 in <a href="https://www.w3.org/TR/CSS22/zindex.html#painting-order">CSS2.2&sect;E.2</a>).
   <!-- Its outline, if any, is painted immediately over its background. -->
   The ''::selection'' overlay is drawn
+  over the ''::target-text'' overlay which is drawn
   over the ''::spelling-error'' overlay
   which is drawn over the ''::grammar-error'' overlay.
 
@@ -1006,6 +1022,7 @@ Changes</h2>
   Changes since the <a href="https://www.w3.org/TR/2019/WD-css-pseudo-4-20190225/">25 February 2019 Working Draft</a> include:
 
   <ul>
+    <li>Added ''::target-text'' pseudo-element.
     <li>Included spaces between the first letter and its surrounding punctuation in ''::first-letter''.
     (<a href="https://github.com/w3c/csswg-drafts/issues/5154">Issue 5154</a>)
     <li>Adjust rules for inheritance of properties from ''::first-line''