intermediate: prepare for js api

web/config.json

@@ -351,7 +351,7 @@
         "check": "checkMinMax",
         "min": -1,
         "max": 256,
-        "description": "the temp instance of PGN 130312 used for water temperature, use -1 for none, 256 for any",
+        "description": "the temp instance of PGN 130312 used for water temperature (0...255), use -1 for none, 256 for any",
         "default": "256",
         "category":"converter"
     },

web/index.css

@@ -340,4 +340,7 @@ body {
 }
 .error{
   color: red;
+}
+.changed input.error{
+  color: red;
 }