[css-grid-1][css-flexbox-1] Commit changes to require percent margin/padding resolution against inline-axis, per WG discussion. #2085

Author: fantasai

css-flexbox-1/Overview.bs

@@ -716,20 +716,12 @@ Flex Item Margins and Paddings</h3>
 	The margins of adjacent <a>flex items</a> do not
 	<a href="https://www.w3.org/TR/CSS2/box.html#collapsing-margins">collapse</a>.
 
-	Percentage margins and paddings on <a>flex items</a> can be resolved against either:
-
-	* their own axis (left/right percentages resolve against width, top/bottom resolve against height), or,
-	* the inline axis (left/right/top/bottom percentages all resolve against width)
-
-	A User Agent must choose one of these two behaviors.
-
-	Note: This variance sucks, but it accurately captures the current state of the world
-	(no consensus among implementations, and no consensus within the CSSWG).
-	It is the CSSWG's intention that browsers will converge on one of the behaviors,
-	at which time the spec will be amended to require that.
-
-	Advisement: Authors should avoid using percentages in paddings or margins on <a>flex items</a> entirely,
-	as they will get different behavior in different browsers.
+	Percentage margins and paddings on <a>flex items</a>,
+	like those on <a>block boxes</a>,
+	are resolved against the <a>inline size</a> of their <a>containing block</a>,
+	e.g. left/right/top/bottom percentages
+	all resolve against their <a>containing block</a>’s <em>width</em>
+	in horizontal <a>writing modes</a>.
 
 	Auto margins expand to absorb extra space in the corresponding dimension.
 	They can be used for alignment,
@@ -3461,6 +3453,12 @@ Boris Zbarsky.
 Changes since the 16 October 2017 CR</h3>
 
 	<ul>
+		<li id="change-2017-margin-padding-percent">
+			Removed the option for flex-item block-axis margins and paddings
+			to be resolved against the block dimension;
+			they must be resolved against the inline dimension, as for blocks.
+			(<a href="https://github.com/w3c/csswg-drafts/issues/2085">Issue 2085</a>)
+
 		<li id="change-2017-content-desc">
 			Added some (effectively informative) prose and a cross-reference
 			to more clearly define ''flex-basis: content''.
@@ -3477,7 +3475,6 @@ Changes since the 16 October 2017 CR</h3>
 			</blockquote>
 	</ul>
 
-
 <h3 id="changes-20160526">
 Changes since the 26 May 2016 CR</h3>
 

css-grid-1/Overview.bs

@@ -1158,24 +1158,15 @@ Grid Item Margins and Paddings</h3>
 	the margins of adjacent <a>grid items</a> do not
 	<a href="https://www.w3.org/TR/CSS2/box.html#collapsing-margins">collapse</a>.
 
-	Percentage margins and paddings on <a>grid items</a> can be resolved against either:
-
-	* their own axis (left/right percentages resolve against width, top/bottom resolve against height), or,
-	* the inline axis (left/right/top/bottom percentages all resolve against width)
-
-	A User Agent must choose one of these two behaviors.
-
-	Note: This variance sucks, but it accurately captures the current state of the world
-	(no consensus among implementations, and no consensus within the CSSWG).
-	It is the CSSWG's intention that browsers will converge on one of the behaviors,
-	at which time the spec will be amended to require that.
-
-	Advisement: Authors should avoid using percentages in paddings or margins on <a>grid items</a> entirely,
-	as they will get different behavior in different browsers.
+	Percentage margins and paddings on <a>grid items</a>,
+	like those on <a>block boxes</a>,
+	are resolved against the <a>inline size</a> of their <a>containing block</a>,
+	e.g. left/right/top/bottom percentages
+	all resolve against their <a>containing block</a>’s <em>width</em>
+	in horizontal <a>writing modes</a>.
 
 	Auto margins expand to absorb extra space in the corresponding dimension,
 	and can therefore be used for alignment.
-
 	See [[#auto-margins]]
 
 <h3 id='z-order'>
@@ -4256,6 +4247,17 @@ Changes</h2>
 <h3 id="changes-2017">
 Changes since the <a href="https://www.w3.org/TR/2017/CR-css-grid-1-20171215/">15 December 2017 CR</a></h3>
 
+<h4 id="major-2017">
+Major Changes</h4>
+
+	<ul>
+		<li id="change-2017-margin-padding-percent">
+			Removed the option for grid-item block-axis margins and paddings
+			to be resolved against the block dimension;
+			they must be resolved against the inline dimension, as for blocks.
+			(<a href="https://github.com/w3c/csswg-drafts/issues/2085">Issue 2085</a>)
+	</ul>
+
 <h4 id="clarify-2017">
 Clarifications</h4>