[css-grid-2] Remove dual-axis subgrid proposal in favor of per-axis subgrids. Closes #2280.

Author: fantasai

css-grid-2/Overview.bs

@@ -16,23 +16,8 @@ Introduction {#intro}
 =====================
 
 	This level is currently maintained as a diff spec over the level 1 module [[!CSS-GRID-1]].
-	The main addition to Level 1 is the “subgrid” feature,
-	which has two proposals:
-
-	<ul>
-		<li>
-			<a href="#subgrid-per-axis">Per-axis Subgrids</a>,
-			which use a ''grid-template-columns/subgrid'' keyword on the 'grid-template' properties
-			to mark one or both axes as subgridded.
-			This proposal is strictly more powerful.
-	 <li>
-			<a href="#subgrid-dual-axis">Dual-axis Subgrids</a>,
-			whic use a ''grid-template-columns/subgrid'' keyword on the 'display' property
-			to mark both axes as subgridded.
-			This proposal is strictly more limited.
-	</ul>
-
-	A subgridded axis is one which matches up its grid lines
+	The main addition to Level 1 is the “subgrid” feature:
+	a subgridded axis is one which matches up its grid lines
 	to lines in the element's parent's grid,
 	and which derives the sizes of its tracks
 	through this integration with the parent grid.
@@ -86,9 +71,8 @@ Subgrids</h2>
 			}
 			li {
 				grid-column: span 2;
-				<del>display: subgrid;</del>
-				<ins>display: grid;
-				grid: subgrid;</ins>
+				display: grid;
+				grid: subgrid;
 				border: solid;
 			}
 			label {
@@ -99,32 +83,6 @@ Subgrids</h2>
 			}
 		</pre>
 	</div>
-<h3 id="subgrid-dual-axis">
-Establishing a Subgrid: Dual-axis Proposal</h3>
-
-	<a>Subgrids</a> provide the ability to pass grid parameters down through nested elements,
-	and content-based sizing information back up to their parent grid.
-
-	<pre class="propdef">
-	Name: display
-	New values: subgrid
-	</pre>
-
-	<dl dfn-for="display" dfn-type=value>
-		<dt><dfn>subgrid</dfn>
-		<dd>
-			If the element is a <a>grid item</a>
-			(i.e. it is in-flow and its parent is a <a>grid container</a>),
-			this value makes the element a <a>subgrid</a>
-			(which is a special type of <a>grid container</a> box, see [[#subgrids]])
-			and consequently ignores its 'grid-template-*' and '*-gap' properties
-			in favor of adopting the parent grid tracks that it spans.
-
-			Otherwise,
-			it behaves as ''grid''.
-	</dl>
-
-	Issue: This syntax only allows for subgrids which are subgridded in both axes.
 
 <h3 id="subgrid-per-axis">
 Establishing a Subgrid: Per-Axis Proposal</h3>
@@ -146,18 +104,16 @@ Establishing a Subgrid: Per-Axis Proposal</h3>
 			the initial value, ''grid-template-rows/none''.
 	</dl>
 
-	Issue: This syntax allows for subgrids which are subgridded in one <em>or</em> both axes.
+	Issue: Add back syntax for overlaying line names.
 
 <h3 id="subgrid-items">
 Characteristics of a Subgrid Item</h3>
 
-	Note: <ins>Insertions</ins> are differences between the dual-axis and per-axis proposals.
-
 	A <a>subgrid</a> behaves just like a normal <a>grid container</a> except that:
 
 	<ul style="list-style-type: lower-alpha">
 		<li>
-			The number of explicit tracks in each <ins>subgridded</ins> dimension
+			The number of explicit tracks in each subgridded dimension
 			is given by its <a>grid span</a> in that dimension,
 			rather than by 'grid-template-rows'/'grid-template-columns'.
 
@@ -169,17 +125,17 @@ Characteristics of a Subgrid Item</h3>
 
 		<li>
 			Since <a>subgrids</a> can be placed before their contents are placed,
-			<del>their</del> <ins>the subgridded</ins> lines
+			the subgridded lines
 			automatically receive the line names specified on the parent <a>grid</a>.
 
 		<li>
 			The <a>subgrid</a> itself lays out as an ordinary <a>grid item</a> in its parent grid,
 			but acts as if it was completely empty for sizing purposes
-			<ins>in the subgridded dimension</ins>.
+			in the subgridded dimension.
 
 			The <a>subgrid</a>'s own <a>grid items</a> participate
-			in the sizing of its parent grid <ins>in the subgridded dimension(s)</ins>
-			and are aligned to it <ins>in those dimensions</ins>.
+			in the sizing of its parent grid in the subgridded dimension(s)
+			and are aligned to it in those dimensions.
 			In this process, the sum of the <a>subgrid</a>'s margin, padding, and borders at each edge
 			are applied as an extra layer of margin to the items at those edges.
 
@@ -212,14 +168,14 @@ Characteristics of a Subgrid Item</h3>
 			</div>
 
 		<li>
-			The 'gap' properties do not apply <del>to subgrids</del>
-			<ins>in the subgridded dimension(s)</ins>.
+			The 'gap' properties do not apply
+			in the subgridded dimension(s).
 			(Their items are instead spaced by the corresponding gutters of their parent grid,
 			since they are laid out in the parent grid.)
 
 		<li>
 			The <a>subgrid</a> does not have any <a>implicit grid tracks</a>
-			<ins>in the subgridded dimension(s)</ins>;
+			in the subgridded dimension(s);
 			every <a>grid area</a> within it is <a>clamped</a> to its <a>explicit grid</a>.
 
 			<div class="example">
@@ -228,15 +184,15 @@ Characteristics of a Subgrid Item</h3>
 			</div>
 
 		<li>
-			The <a>subgrid</a> is always stretched <del>in both dimensions</del> <ins>in its subgridded dimension(s)</ins>:
+			The <a>subgrid</a> is always stretched in its subgridded dimension(s:
 			the 'align-self'/'justify-self' properties on it are ignored,
 			as are any specified width/height constraints.
 
 		<li>
 			Layoutwise, the <a>subgrid</a>’s <a>grid</a>
 			is always aligned with the corresponding section of the parent <a>grid</a>;
 			the 'align-content'/'justify-content' properties on it are also ignored
-			<ins>in the subgridded dimension</ins>.
+			in the subgridded dimension.
 
 		<li>
 			The UA <em>may</em> apply 'overflow' to <a>subgrids</a>
@@ -252,10 +208,6 @@ Subgrid Sizing Algorithm</h3>
 	including subgrids and their sub-items,
 	occurs before sizing.
 
-	Issue: In this section, which is itself a diff,
-	<i>italics</i> indicate additional prose
-	specific to <a href="#subgrid-per-axis">per-axis subgrids</a>.
-
 	Track sizing in a subgridded dimension
 	treats each item in a given track in that axis
 	as members of the parent grid.
@@ -271,17 +223,15 @@ Subgrid Sizing Algorithm</h3>
 		<li>
 			First, the <a>track sizing algorithm</a> is used to resolve the sizes of the <a>grid columns</a>.
 
-			<ins>
-
-			<p>In this process,
+			In this process,
 			any <a>grid item</a> which is subgridded
 			in the <a>grid container</a>’s <a>inline axis</a>
 			is treated as empty
 			and its <a>grid items</a> (the grandchildren)
 			are treated as direct children of the <a>grid container</a> (their grandparent).
 			This introspection is recursive.
 
-			<p><i>Items which are subgridded only in the <a>block axis</a>,
+			Items which are subgridded only in the <a>block axis</a>,
 			and whose <a>grid container</a> size in the <a>inline axis</a>
 			depends on the size of its contents
 			are also introspected:
@@ -298,9 +248,7 @@ Subgrid Sizing Algorithm</h3>
 			the item will have completed a first pass through steps 1-3
 			as well as the second pass of this step
 			prior to returning its size for consideration in this grid’s column sizing.
-			Again, this introspection is recursive.</i></p>
-
-			</ins>
+			Again, this introspection is recursive.
 
 			If calculating the layout of a <a>grid item</a> in this step
 			depends on the <a>available space</a> in the <a>block axis</a>,
@@ -312,17 +260,15 @@ Subgrid Sizing Algorithm</h3>
 			Next, the <a>track sizing algorithm</a> resolves the sizes of the <a>grid rows</a>,
 			using the <a>grid column</a> sizes calculated in the previous step.
 
-			<ins>
-
-			<p>In this process,
+			In this process,
 			any <a>grid item</a> which is subgridded
 			in the <a>grid container</a>’s <a>block axis</a>
 			is treated as empty
 			and its <a>grid items</a> (the grandchildren)
 			are treated as direct children of the <a>grid container</a> (their grandparent).
 			This introspection is recursive.
 
-			<p><i>As with sizing columns,
+			As with sizing columns,
 			items which are subgridded only in the <a>inline axis</a>,
 			and whose <a>grid container</a> size in the <a>block axis</a>
 			depends on the size of its contents
@@ -332,8 +278,7 @@ Subgrid Sizing Algorithm</h3>
 			is taken under the provision
 			of having determined its track sizing
 			only up to this corresponding point in the algorithm;
-			and again, this introspection is recursive.)</i></p>
-			</ins>
+			and again, this introspection is recursive.)
 
 		<li>
 			Then, if the <a>min-content contribution</a> of any grid items have changed
@@ -377,10 +322,10 @@ Subgrid Sizing Algorithm</h3>
 	We could simplify this by saying that an orthogonal flow
 	cannot establish a subgrid; it can only be a nested grid.
 
-	<i>The following example illustrates how per-axis subgrids are sized:</i>
+	<div class="example">
+		The following example illustrates how per-axis subgrids are sized:
 
-	<div class="example" style="font-style: italic">
-		For example, suppose we have a parent grid container <var>A</var>
+		Suppose we have a parent grid container <var>A</var>
 		which contains an item <var>B</var> that has subgridded columns
 		and contains a grandchild <var>B</var> that has subgridded rows
 		and grandchild <var>D</var> that is simply a nested grid.