diff --git a/source b/source
index dc6e47875ce..79ade017fb3 100644
--- a/source
+++ b/source
@@ -3326,10 +3326,6 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
     define how the Fullscreen API interacts with HTML: <ref spec=FULLSCREEN></p>
 
     <ul class="brief">
-     <li><dfn data-x-href="https://fullscreen.spec.whatwg.org/#top-layer">top layer</dfn> (an
-         <span data-x="set">ordered set</span>) and its
-         <dfn data-x="top-layer-add" data-x-href="https://fullscreen.spec.whatwg.org/#top-layer-add">add</dfn>
-         operation</li>
      <li><dfn data-x-href="https://fullscreen.spec.whatwg.org/#dom-element-requestfullscreen"><code data-x="dom-element-requestFullscreen">requestFullscreen()</code></dfn></li>
      <li><dfn data-x-href="https://fullscreen.spec.whatwg.org/#run-the-fullscreen-steps">run the fullscreen steps</dfn></li>
      <li><dfn data-x-href="https://fullscreen.spec.whatwg.org/#fullscreen-flag">fullscreen flag</dfn></li>
@@ -3799,6 +3795,12 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
       <li><dfn data-x-href="https://drafts.csswg.org/css-position/#absolute-position">absolutely-positioned</dfn></li>
       <li>The <dfn data-x-href="https://drafts.csswg.org/css-position/#position-property">'position'</dfn> property and its
               <dfn data-x-href="https://drafts.csswg.org/css-position/#valdef-position-static">'static'</dfn> value</li>
+      <li>The <dfn data-x-href="https://drafts.csswg.org/css-position-4/#document-top-layer">top layer</dfn>
+              (an <span data-x="set">ordered set</span>)</li>
+      <li><dfn data-x-href="https://drafts.csswg.org/css-position-4/#add-an-element-to-the-top-layer">add an element to the top layer</dfn></li>
+      <li><dfn data-x-href="https://drafts.csswg.org/css-position-4/#request-an-element-to-be-removed-from-the-top-layer">request an element to be removed from the top layer</dfn></li>
+      <li><dfn data-x-href="https://drafts.csswg.org/css-position-4/#remove-an-element-from-the-top-layer-immediately">remove an element from the top layer immediately</dfn></li>
+      <li><dfn data-x-href="https://drafts.csswg.org/css-position-4/#process-top-layer-removals">process top layer removals</dfn></li>
     </ul>
 
     <p>The following features are defined in <cite>CSS Multi-column Layout</cite>. <ref
@@ -60366,9 +60368,8 @@ interface <dfn interface>HTMLDialogElement</dfn> : <span>HTMLElement</span> {
    </li>
 
    <li><p>If <span>this</span>'s <span>node document</span>'s <span>top layer</span> does not
-   already <span data-x="list contains">contain</span> <span>this</span>, then <span
-   data-x="top-layer-add">add</span> <span>this</span> to <span>this</span>'s <span>node
-   document</span>'s <span>top layer</span>.</p></li>
+   already <span data-x="list contains">contain</span> <span>this</span>, then <span>add an element
+   to the top layer</span> given <span>this</span>.</p></li>
 
    <li><p>Set <span>this</span>'s <span>previously focused element</span> to the
    <span>focused</span> element.</p></li>
@@ -60418,11 +60419,10 @@ interface <dfn interface>HTMLDialogElement</dfn> : <span>HTMLElement</span> {
    <li><p>Set <var>topDocument</var>'s <span>autofocus processed flag</span> to true.</p></li>
   </ol>
 
-  <p>If at any time a <code>dialog</code> element is <span data-x="node is removed from a
-  document">removed from a <code>Document</code></span>, then if that <code>dialog</code> is in that
-  <code>Document</code>'s <span>top layer</span>, it must be <span
-  data-x="list remove">removed</span> from it. Also, set the <code>dialog</code> element's
-  <span>is modal</span> flag to false.
+  <p>The <code>dialog</code> <span>HTML element removing steps</span>, given <var>removedNode</var>
+  and <var>oldParent</var>, are if <var>removedNode</var>'s <span>node document</span>'s <span>top
+  layer</span> <span data-x="list contains">contains</span> <var>removedNode</var>, then
+  <span>remove an element from the top layer immediately</span> given <var>removedNode</var>.</p>
 
   <p>The <dfn method for="HTMLDialogElement"><code
   data-x="dom-dialog-close">close(<var>returnValue</var>)</code></dfn> method steps are:
@@ -60443,8 +60443,8 @@ interface <dfn interface>HTMLDialogElement</dfn> : <span>HTMLElement</span> {
    <li><p>Remove <var>subject</var>'s <code data-x="attr-dialog-open">open</code>
    attribute.</p></li>
 
-   <li><p>If the <span>is modal</span> flag of <var>subject</var> is true, then <span data-x="list
-   remove">remove</span> it from its <code>Document</code>'s <span>top layer</span>.</p></li>
+   <li><p>If the <span>is modal</span> flag of <var>subject</var> is true, then <span>request an
+   element to be removed from the top layer</span> given <var>subject</var>.</p></li>
 
    <li><p>Let <var>wasModal</var> be the value of <var>subject</var>'s <span>is
    modal</span> flag.</p></li>
@@ -77023,9 +77023,9 @@ interface <dfn interface>VisibilityStateEntry</dfn> : <span>PerformanceEntry</sp
   tree</span> descendants can become <span>inert</span> in a similar fashion.</p>
 
   <p class="note">The <code>dialog</code> element's <code
-  data-x="dom-dialog-showModal">showModal()</code> method causes this mechanism to trigger, by
-  <span data-x="top-layer-add">adding</span> the <code>dialog</code> element to its <span>node
-  document</span>'s <span>top layer</span>.</p>
+  data-x="dom-dialog-showModal">showModal()</code> method causes this mechanism to trigger, by <span
+  data-x="add an element to the top layer">adding</span> the <code>dialog</code> element to its
+  <span>node document</span>'s <span>top layer</span>.</p>
 
   <h4>The <dfn data-x="attr-inert"><code>inert</code></dfn> attribute</h4>
 
@@ -82561,7 +82561,7 @@ dictionary <dfn dictionary>DragEventInit</dfn> : <span>MouseEventInit</span> {
    <li><p>Let <var>originallyFocusedElement</var> be <var>document</var>'s <span>focused area of the
    document</span>'s <span>DOM anchor</span>.</p></li>
 
-   <li><p>Add <var>element</var> to <var>document</var>'s <span>top layer</span>.</p></li>
+   <li><p><span>Add an element to the top layer</span> given <var>element</var>.</p></li>
 
    <li><p>Set <var>element</var>'s <span>popover visibility state</span> to <span
    data-x="popover-showing-state">showing</span>.</p></li>
@@ -82696,11 +82696,14 @@ dictionary <dfn dictionary>DragEventInit</dfn> : <span>MouseEventInit</span> {
       data-x="event-beforetoggle">beforetoggle</code> event could have disconnected
       <var>element</var> or changed its <code data-x="attr-popover">popover</code> attribute.</p>
      </li>
+
+     <li><p><span>Request an element to be removed from the top layer</span> given
+     <var>element</var>.</p></li>
     </ol>
    </li>
 
-   <li><p><span data-x="list remove">Remove</span> <var>element</var> from the <span>top
-   layer</span>.</p></li>
+   <li><p>Otherwise, <span>remove an element from the top layer immediately</span> given
+   <var>element</var>.</p></li>
 
    <li><p>Set <var>element</var>'s <span>popover visibility state</span> to <span
    data-x="popover-hidden-state">hidden</span>.</p></li>
@@ -102364,6 +102367,9 @@ import "https://example.com/foo/../module2.mjs";</code></pre>
      <li><p>For each <span>fully active</span> <code>Document</code> in <var>docs</var>, update the
      rendering or user interface of that <code>Document</code> and its <span>node navigable</span>
      to reflect the current state.</p></li>
+
+     <li><p>For each <span>fully active</span> <code>Document</code> <var>doc</var> in
+     <var>docs</var> run <span>process top layer removals</span> given <var>doc</var>.</p></li>
     </ol>
    </li>