Affinity: Use post width, not page width, for Affinity's editor style.

affinity/editor-blocks.css

@@ -146,7 +146,7 @@
 /* Main column width */
 
 .wp-block {
-	max-width: 746px; /* 716px + 30px padding */
+	max-width: 567px; /* 537px + 30px padding */
 }
 
 /* Link styles */