[css-grid] Distribute space to intrinsic flexible tracks continuously between zero and one. w3c#6078

Author: fantasai

css-grid-1/Overview.bs

@@ -4285,10 +4285,14 @@ Resolve Intrinsic Track Sizes</h3>
 				<li>
 					if the sum of the <a>flexible sizing functions</a>
 					of all <a>flexible tracks</a> spanned by the item
-					is greater than zero,
+					is greater than or equal to one,
 					distributing space to such tracks
 					according to the ratios of their <a>flexible sizing functions</a>
-					rather than distributing space equally
+					rather than distributing space equally;
+					and if the sum is less than one,
+					distributing that proportion of space
+					according to the ratios of their <a>flexible sizing functions</a>
+					and the rest equally
 			</ul>
 
 		<li id="algo-finite-growth">
@@ -4690,21 +4694,43 @@ Changes</h2>
 Changes since the <a href="https://www.w3.org/TR/2020/CRD-css-grid-1-20201218/">18 December 2020 CR</a></h3>
 
 	<ul class="non-normative">
+		<li id="change-2020-flex-intrinsic-ratios">
+			Changed intrinsic track space distribution [[#algo-spanning-flex-items|across flexible tracks]]
+			for flex sums between zero and one to interpolate
+			between ratio-relative and equal distribution
+			for continuity from zero.
+			(<a href="https://github.com/w3c/csswg-drafts/issues/6078">Issue 6078</a>)
+			<blockquote>
+				<p>if the sum of the <a>flexible sizing functions</a>
+				of all <a>flexible tracks</a> spanned by the item
+				is greater than <del>zero</del><ins>or equal to one</ins>,
+				distributing space to such tracks
+				according to the ratios of their <a>flexible sizing functions</a>
+				rather than distributing space equally<ins>;
+				and if the sum is less than one,
+				distributing that proportion of space
+				according to the ratios of their <a>flexible sizing functions</a>
+				and the rest equally</ins></p>
+			</blockquote>
+
 		<li id="change-2020-auto-min-contribution">
 			Clarified that the [=content-based minimum size=] of a grid item
 			is a type of [=intrinsic size contribution=],
 			and thus impacted by associated rules in [[CSS-SIZING-3]].
 			(<a href="https://github.com/w3c/csswg-drafts/issues/5665#issuecomment-738391191">Issue 5665</a>)
+
 		<li id="change-2020-auto-min-replaced">
 			Explicitly restricted the application of the [=transferred size suggestion=]
 			to [=replaced elements=] as was originally intended,
 			now that [=non-replaced elements=] can also have an aspect ratio
 			via 'aspect-ratio'. [[CSS-SIZING-4]]
 			(<a href="https://github.com/w3c/csswg-drafts/issues/6069">Issue 6069</a>)
+
 		<li id="change-2020-auto-margins">
 			Made [[#auto-margins]] normative and tightened up wording,
 			since some aspects of this behavior were not otherwise defined elsewhere.
 			(part of <a href="https://github.com/w3c/csswg-drafts/issues/5923">Issue 5923</a>)
+
 		<li id="change-2020-content-distribution-stretch">
 			Condition [[#algo-stretch]] on the relevant [=content-distribution property=]
 			behaving as ''justify-content/stretch'';

css-grid-2/Overview.bs

@@ -4962,10 +4962,14 @@ Resolve Intrinsic Track Sizes</h3>
 				<li>
 					if the sum of the <a>flexible sizing functions</a>
 					of all <a>flexible tracks</a> spanned by the item
-					is greater than zero,
+					is greater than or equal to one,
 					distributing space to such tracks
 					according to the ratios of their <a>flexible sizing functions</a>
-					rather than distributing space equally
+					rather than distributing space equally;
+					and if the sum is less than one,
+					distributing that proportion of space
+					according to the ratios of their <a>flexible sizing functions</a>
+					and the rest equally
 			</ul>
 
 		<li id="algo-finite-growth">
@@ -5332,21 +5336,43 @@ Changes</h2>
 Changes since the <a href="https://www.w3.org/TR/2020/CRD-css-grid-2-20201218/">18 December 2020 CR</a></h3>
 
 	<ul class="non-normative">
+		<li id="change-2020-flex-intrinsic-ratios">
+			Changed intrinsic track space distribution [[#algo-spanning-flex-items|across flexible tracks]]
+			for flex sums between zero and one to interpolate
+			between ratio-relative and equal distribution
+			for continuity from zero.
+			(<a href="https://github.com/w3c/csswg-drafts/issues/6078">Issue 6078</a>)
+			<blockquote>
+				<p>if the sum of the <a>flexible sizing functions</a>
+				of all <a>flexible tracks</a> spanned by the item
+				is greater than <del>zero</del><ins>or equal to one</ins>,
+				distributing space to such tracks
+				according to the ratios of their <a>flexible sizing functions</a>
+				rather than distributing space equally<ins>;
+				and if the sum is less than one,
+				distributing that proportion of space
+				according to the ratios of their <a>flexible sizing functions</a>
+				and the rest equally</ins></p>
+			</blockquote>
+
 		<li id="change-2020-auto-min-contribution">
 			Clarified that the [=content-based minimum size=] of a grid item
 			is a type of [=intrinsic size contribution=],
 			and thus impacted by associated rules in [[CSS-SIZING-3]].
 			(<a href="https://github.com/w3c/csswg-drafts/issues/5665#issuecomment-738391191">Issue 5665</a>)
+
 		<li id="change-2020-auto-min-replaced">
 			Explicitly restricted the application of the [=transferred size suggestion=]
 			to [=replaced elements=] as was originally intended,
 			now that [=non-replaced elements=] can also have an aspect ratio
 			via 'aspect-ratio'. [[CSS-SIZING-4]]
 			(<a href="https://github.com/w3c/csswg-drafts/issues/6069">Issue 6069</a>)
+
 		<li id="change-2020-auto-margins">
 			Made [[#auto-margins]] normative and tightened up wording,
 			since some aspects of this behavior were not otherwise defined elsewhere.
 			(part of <a href="https://github.com/w3c/csswg-drafts/issues/5923">Issue 5923</a>)
+
 		<li id="change-2020-content-distribution-stretch">
 			Condition [[#algo-stretch]] on the relevant [=content-distribution property=]
 			behaving as ''justify-content/stretch'';