[css-grid-1] Add gutter clarification to changes list. #2201

Author: fantasai

css-grid-1/Overview.bs

@@ -4253,6 +4253,37 @@ Changes</h2>
 
 	This section documents the changes since previous publications.
 
+<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="clarify-2017">
+Clarifications</h4>
+
+	<ul>
+		<li id="change-2017-gutter-tracks">
+			Added reminder to <a>track sizing algorithm</a>
+			that gutters are treated as fixed-size tracks;
+			clarified their relationship to spanning items
+			(they are spanned by the same items as their lines, of course).
+			(<a href="https://github.com/w3c/csswg-drafts/issues/2201">Issue 2201</a>)
+			<blockquote>
+				<p>For the purpose of [[#algo-track-sizing|track sizing]],
+				each <a>gutter</a> is treated as
+				an extra, empty<ins>, fixed-size</ins> track of the specified size<ins>,
+				which is spanned by any <a>grid items</a>
+				that span across its corresponding <a>grid line</a></ins>.
+			</blockquote>
+			<blockquote>
+				<h3>Track Sizing Terminology</h3>
+
+				<p class="note"><ins>Note: Remember that <a href="#gutters">gutters</a> are treated as fixed-size tracks--
+				tracks with their min and max sizing functions both set to the gutter’s used size--
+				for the purpose of the grid sizing algorithm.
+				Their widths need to be incorporated into
+				the <a>track sizing algorithm</a>’s calculations accordingly.</ins>
+			</blockquote>
+	</ul>
+
 <h3 id="changes-2016">
 Changes since the <a href="https://www.w3.org/TR/2016/CR-css-grid-1-20160929/">29 September 2016 CR</a></h3>
 
@@ -4593,7 +4624,7 @@ Significant Adjustments and Fixes</h4>
 <h4 id="clarify-2016">
 Clarifications</h4>
 
-	<ul id="change-2016-auto-min-editorial">
+	<ul>
 		<li id="change-2016-fit-content-stretch">
 			Clarified that ''fit-content()'' is not affected by ''align-content/stretch'' 'align-content'/'justify-content'.
 			(<a href="https://github.com/w3c/csswg-drafts/issues/1732">Issue 1732</a>)
@@ -4605,7 +4636,7 @@ Clarifications</h4>
 				if it is greater than the ''auto'' minimum.
 			</blockquote>
 
-		<li>
+		<li id="change-2016-auto-min-editorial">
 			Clarified definition of <a>min-size contribution</a>.
 			(<a href="https://github.com/w3c/csswg-drafts/issues/507">Issue #507</a>)
 			<blockquote>