[css-align] Make 'normal' compute to zero except on multicol.

Author: fantasai

css-align/Overview.bs

@@ -1609,7 +1609,7 @@ The 'column-gap', 'row-gap', and 'gap' Properties</h3>
 	Inherited: no
 	Percentages: refer to corresponding dimension of the content area
 	Media: visual
-	Computed value: as specified, with <<length>>s made absolute
+	Computed value: as specified, with <<length>>s made absolute, and''row-gap/normal'' computing to zero except on <a>multi-column elements</a>
 	Animatable: as length, percentage, or calc
 	</pre>
 
@@ -1642,13 +1642,11 @@ The 'column-gap', 'row-gap', and 'gap' Properties</h3>
 			Negative values are invalid.
 
 		: <dfn>normal</dfn>
-		:: The ''gap/normal'' value is identical to some <<length-percentage>>,
-			but precisely which value depends on the layout mode,
-			and is sometimes UA-dependent;
-			see subsections below for details.
-	</dl>
+		:: The ''gap/normal'' represents a UA-dependent length on <a>multi-column elements</a>,
+			and computes to ''0px'' in all other contexts.
 
-	Note: In addition to the [=gutters=] defined by these properties,
+			Issue: Should ''gap/normal'' just compute to ''1em'' in multicol?
+	</dl>
 
 
 <h4 id='gap-multicol'>
@@ -1657,19 +1655,13 @@ Multicol Containers</h4>
 	'column-gap' specifes the [=gutter=] between adjacent <a>column boxes</a>.
 	See [[CSS-MULTICOL-1]] for details on how this affects the layout of multicol elements.
 
-	The ''gap/normal'' value behaves as a UA-specified length for 'column-gap'.
-	It's suggested that this be equal to ''1em''.
-
 	Multicol does not currently use 'row-gap'.
-	For it, ''gap/normal'' behaves as ''0''.
 
 <h4 id='gap-flex'>
 Flex Containers</h4>
 
 	Issue: TODO define how row-gap/column-gap work between flex items and flex lines.
 
-	''gap/normal'' behaves as ''0'' for both properties.
-
 <h4 id='gap-grid'>
 Grid Containers</h4>