[css-page-floats] make page float placement depend on placement of float in DOM and level of float reference + cleanup

Author: johanneswilm

css-page-floats/Overview.bs

@@ -794,8 +794,25 @@ img {
 
 <h2 id="page-float-placement">Page float placement</h2>
 
-  Page floats are placed one by one in the order they appear in the DOM. The
-  placement of a single page float is a process that has to be terminated
+  The order of page float placement is determined by the following rules:
+
+  <ol>
+  <li>
+    A page float is placed before any page floats with a <a>float reference</a>
+    that is a descendant of its <a>float reference</a>.
+  </li>
+  <li>
+    Page floats with the same <a>float reference</a> are placed in the order they
+    appear in the DOM.
+  </li>
+  <li>
+    Page floats whose float references are not descendants of one-another and
+    that do not have the same <a>float reference</a> are placed in the order
+    they appear in the DOM.
+  </li>
+  </ol>
+
+  The placement of a single page float is a process that has to be terminated
   entirely before the placement of a subsequent page float can be initiated. The
   placement process consists of the following steps:
 
@@ -807,14 +824,15 @@ img {
     initially set to be the same as the <a>initial float reference</a>.</li>
 
     <li>Determine if the given <a>float reference</a> has enough space or can be
-    expanded to host the page float, if the rules of 'float stacking' and 'float
-    reference growth' are to be followed. If this is not the case, and the
-    <a>float reference</a> is not the last <a>fragmentation container</a> within the given
-    <a>fragmentation context</a>, then make the following <a>fragmentation container</a>
-    within the given <a>fragmentation context</a> the <a>float reference</a>. Repeat this
-    step until the <a>float reference</a> can be expanded enough to host the page
-    float or it is the last <a>fragmentation container</a> within the given
-    <a>fragmentation context</a>.</li>
+    expanded to host the page float, if the rules of <a href="#float-stacking">
+    float stacking</a> and <a href="#float-reference-growth">float reference
+    growth</a> are to be followed. If this is not the case, and the <a>float
+    reference</a> is not the last <a>fragmentation container</a> within the given
+    <a>fragmentation context</a>, then make the following <a>fragmentation
+    container</a> within the given <a>fragmentation context</a> the <a>float
+    reference</a>. Repeat this step until the <a>float reference</a> can be
+    expanded enough to host the page float or it is the last <a>fragmentation
+    container</a> within the given <a>fragmentation context</a>.</li>
 
     <li>If the <a>float reference</a> is the last <a>fragmentation container</a> within
     the given <a>fragmentation context</a>, and it has not enough space and cannot be
@@ -823,9 +841,10 @@ img {
     <ol>
       <li>If the <a>fragmentation context</a> allows for the addition of another
       <a>fragmentation container</a> and an additional <a>fragmentation container</a>
-      would have the needed size to host the page float, a new 'fragmentation
-      container' is added to the end of the <a>fragmentation context</a>. The 'float
-      reference' is set the newly created <a>fragmentation container</a>.</li>
+      would have the needed size to host the page float, a new <a>fragmentation
+      container</a> is added to the end of the <a>fragmentation context</a>. The
+      <a>float reference</a> is set the newly created <a>fragmentation
+      container</a>.</li>
 
       <li>Otherwise, if the <a>fragmentation container</a> is a region, then the
       'regionOverset` attribute of the <a>fragmentation container</a> is set to
@@ -854,7 +873,7 @@ float with the same <a>float reference</a> and the same 'float' value, where N i
 the 'float-offset' value of the page float. For the placement it is assumed that
 the page floats in the block directions fill the entire line size of the <a>float
 reference</a> and page floats in the inline direction fill the entire block size
-of the <a>float reference<a>.
+of the <a>float reference</a>.
 
 If the page float has a defined 'clear'-value, then the <a>float reference</a> in
 which the page float is placed is closed for all subsequent page floats that
@@ -1075,9 +1094,14 @@ p { float-reference: page; float: top; float-defer: last }
   :
 
   <ol>
+    <li>
+      Make the order of page float placement determined both by DOM and how high
+      in the DOM the page float reference is.
+    </li>
     <li>
       Specify use of padding edges for float references and margin edges for page
       floats for placement.
+    </li>
     <li>
       Term change: fragmentation flow -> fragmentation context.
     </li>