[css-values-4] Revert accidental commit to css-values-4 from css-display-3 commit 1432231

Author: fantasai

css-values-4/Overview.bs

@@ -1680,8 +1680,11 @@ Syntax</h4>
 	<<min()>>  = min( <<calc-sum>># )
 	<<max()>>  = max( <<calc-sum>># )
 	<dfn>&lt;calc-sum></dfn> = <<calc-product>> [ [ '+' | '-' ] <<calc-product>> ]*
-	<dfn>&lt;calc-product></dfn> = <<calc-value>> [ '*' <<calc-value>> | '/' <<calc-value>> ]*
+	<dfn>&lt;calc-product></dfn> = <<calc-value>> [ '*' <<calc-value>> | '/' <<calc-number-value>> ]*
 	<dfn>&lt;calc-value></dfn> = <<number>> | <<dimension>> | <<percentage>> | ( <<calc-sum>> )
+	<dfn>&lt;calc-number-sum></dfn> = <<calc-number-product>> [ [ '+' | '-' ] <<calc-number-product>> ]*
+	<dfn>&lt;calc-number-product></dfn> = <<calc-number-value>> [ '*' <<calc-number-value>> | '/' <<calc-number-value>> ]*
+	<dfn>&lt;calc-number-value></dfn> = <<number>> | ( <<calc-number-sum>> )
 	</pre>
 
 	In addition, [=whitespace=]