formal grammar now requires white space around + and -

Author: howcom

css3-values/Overview.src.html

@@ -523,7 +523,7 @@ <h4>The 'calc', 'min' and 'max' functions</h4>
 calc    : "calc(" S* sum ")" S*;
 min     : "min(" S* sum [ "," S* sum ]* )"" S*;
 max     : "max(" S* sum [ "," S* sum ]* ")" S*;
-sum     : product [ [ "+" | "-" ] S* product ]*;
+sum     : product [ S+ [ "+" | "-" ] S+ product ]*;
 product : unit [[ "*" S* unit ] | [ "/" S* NUMBER ]] *;
 unit    : ["+"|"-"]? [ NUMBER S* | DIMENSION S* | PERCENTAGE S* |
           min | max | "(" S* sum ")" S* ];