[css-contain-3] Query units select appropriate containers

Author: mirisuzanne

css-contain-3/Overview.bs

@@ -559,15 +559,17 @@ Style Container Features</h3>
 	<dfn export>Style queries</dfn> allow querying
 	the [=computed values=] of the [=query container=].
 
+	Issue(6396): Define a syntax for style-based container queries
 
 <h3 id="state-container">
 State Container Features</h3>
 
 	<dfn export>State queries</dfn> allow querying
-	miscellaneous states such as
+	miscellaneous [=query container=] states, such as
 	whether a ''position: sticky'' box is displaced from its in-flow position,
 	or whether the box is visible on screen.
 
+Issue: Define a syntax for state-based container queries
 
 <h2 id="container-lengths">
 Container Relative Lengths: the ''qw'', ''qh'', ''qi'', ''qb'', ''qmin'', ''qmax'' units</h2>
@@ -586,38 +588,44 @@ Container Relative Lengths: the ''qw'', ''qh'', ''qi'', ''qb'', ''qmin'', ''qmax
 	</thead>
 	<tbody>
 		<tr><td>''qw''
-			<td>1% of [=query container=]'s width
+			<td>1% of a [=query container=]'s [=width=]
 		<tr><td>''qh''
-			<td>1% of [=query container=]'s height
+			<td>1% of a [=query container=]'s [=height=]
 		<tr><td>''qi''
-			<td>1% of [=query container=]'s inline size
+			<td>1% of a [=query container=]'s [=inline size=]
 		<tr><td>''qb''
-			<td>1% of [=query container=]'s block size
+			<td>1% of a [=query container=]'s [=block size=]
 		<tr><td>''qmin''
-			<td>1% of [=query container=]'s smaller dimension
+			<td>The smaller value of ''qi'' or ''qb''
 		<tr><td>''qmax''
-			<td>1% of [=query container=]'s larger dimension
+			<td>The larger value of ''qi'' or ''qb''
 	</tbody>
 	</table>
 
-	Child elements do not inherit the relative values as specified for their parent;
-	they inherit the <a>computed values</a>.
-
 	For each element,
 	[=container length=] units are evaluated
 	as [=dimensional queries=] on the relevant axis or axes
 	described by the unit.
-	The [=query container=] is always the nearest ancestor container.
-	If the query cannot be evaluated,
-	then the [=container length=] is zero (''0'').
+	The [=query container=] for each axis
+	is the nearest ancestor container
+	that accepts [=dimensional queries=] on that axis.
+	If no eligible [=query container=] is defined on the required axis,
+	then the [=container length=] on that axis is zero (''0'').
+
+	Note: In some cases ''qi'' and ''qb'' units on the same element
+	will evaluate in relation to different [=query containers=].
+	Similarly, ''qmin'' and ''qmax'' units represent
+	the larger or smaller of the ''qi'' and ''qb'' units,
+	even when those dimensions come from different [=query containers=].
+
+	Child elements do not inherit the relative values as specified for their parent;
+	they inherit the <a>computed values</a>.
 
 	<div class=example>
 		Since container relative units rely on being inside a proper container,
-		it's best to establish a fallback value.
-		The ''calc()'', ''min()'', ''max()'', and ''clamp()'' functions
-		can all help with this situation.
-
-		Consider these uses, assuming there is no container:
+		and fallback to ''0'',
+		it's often useful to establish a minimum value using math functions
+		like ''calc()'', ''min()'', ''max()'', or ''clamp()'':
 
 		<pre class=lang-css>
 		article {