enhance (& fix for mobile) styling and verbiage

README.md

@@ -90,6 +90,7 @@ To add an icon, add to main.ts and reference with `fa` element and `icon` attrib
   - As the new user on the home page, check that they can now record a gift.
   - On the contacts page, check that they cannot register someone else yet.
 - Walk through the functions on each page.
+- Test the mobile view.
 
 
 
@@ -116,6 +117,16 @@ To add an icon, add to main.ts and reference with `fa` element and `icon` attrib
 
 
 
+## Troubleshooting
+
+* A problem with `GET http://localhost:8080/web-push/vapid` means the py-push-server is not running
+  (and it won't work for a local app, anyway).
+
+* Red errors everywhere with a console message like this:
+  `Error: An ID is chosen but there are no keys for it so it cannot be used to talk with the service`
+  ... has happened on account switching when the current account was erased (or maybe replaced -- once I had a duplicate and I don't know how).
+
+
 
 ## Other