syntax: makefile: color comments only at start of line or after whitespace

syntax/makefile.nanorc

@@ -7,7 +7,7 @@ color red "[:=]"
 color magenta "\<(if|ifeq|else|endif)\>"
 color blue "\$+[{(][a-zA-Z0-9_-]+[})]"
 color brightblue "^[^ 	]+:"
-color green "#.*$"
+color green "(^|[[:space:]]+)#.*"
 
 ## Trailing whitespace.
 color ,green "[[:space:]]+$"