[css-grid-1] Per WG resolution, zero out the automatic minimum contribution of a spanning item if it crosses a flexible track. w3c#4783.

Author: tabatkins

css-grid-1/Overview.bs

@@ -1285,12 +1285,15 @@ Automatic Minimum Size of Grid Items</h3>
 	is defined in <a href="https://www.w3.org/TR/css-sizing-3/">CSS Intrinsic and Extrinsic Sizing</a> [[!CSS-SIZING-3]].
 
 	To provide a more reasonable default <a>minimum size</a> for <a>grid items</a>,
-	the used value of an <a>automatic minimum size</a> in a given axis
-	on a <a>grid item</a> that is not a <a>scroll container</a>
-	and that spans at least one <a>track</a> in that axis
-	whose <a>min track sizing function</a> is ''grid-template-rows/auto''
-	is its <a>content-based minimum size</a>;
-	the used <a>automatic minimum size</a> is otherwise zero, as usual.
+	the used value of its <a>automatic minimum size</a> in a given axis
+	is the <a>content-based minimum size</a> if all of the following are true:
+
+	* it is not a [=scroll container=]
+	* it spans at least one [=track=] in that axis
+		whose <a>min track sizing function</a> is ''grid-template-rows/auto''
+	* if it spans more than one track in that axis, none of those tracks are [=flexible track|flexible=]
+
+	Otherwise, the [=automatic minimum size=] is zero, as usual.
 
 	The <dfn>content-based minimum size</dfn> for a <a>grid item</a> in a given dimension is
 	its <a>specified size suggestion</a> if it exists,
@@ -4910,6 +4913,32 @@ Major Changes</h4>
 		<wpt>
 		layout-algorithm/flex-and-intrinsic-sizes-001.html
 		</wpt>
+
+		<li id="change-2017-auto-min-across-flex">
+			Also zeroed out the automatic minimum contribution of a grid item
+			if it spans multiple tracks,
+			at least one of which is flexible.
+			(<a href="https://github.com/w3c/csswg-drafts/issues/4783">Issue 4783</a>)
+
+			<blockquote>
+				<p>To provide a more reasonable default <a>minimum size</a> for <a>grid items</a>,
+				the used value of <del>an</del> <ins>its</ins> <a>automatic minimum size</a> in a given axis
+				<del>on a <a>grid item</a> that is not a <a>scroll container</a>
+				and that spans at least one <a>track</a> in that axis
+				whose <a>min track sizing function</a> is ''grid-template-rows/auto''</del>
+				is its <a>content-based minimum size</a><del>;</del> <ins>if all of the following are true:</ins></p>
+
+				<ins>
+					<ul>
+						<li>it is not a scroll container
+						<li>it spans at least one [=track=] in that axis
+							whose <a>min track sizing function</a> is ''grid-template-rows/auto''
+						<li><strong>if it spans more than one track in that axis, none of those tracks are [=flexible track|flexible=]</strong>
+					</ul>
+				</ins>
+
+				<p><ins>Otherwise, the used <a>automatic minimum size</a> is <del>otherwise</del> zero, as usual.</p>
+			</blockquote>
 	</ul>
 <h4 id="minor-2017">
 Minor Changes</h4>