Don't know if this would help you in any way but here's the debug message when visiting the demo site:
Code:
Nov 1 14:26:39 nickel: ( 5335.603 @ 0x4c7898 / ui.debug) "http://demo.signalk.org/admin/:1: Viewport argument key "shrink-to-fit" not recognized and ignored."
Nov 1 14:26:41 nickel: ( 5337.170 @ 0x4c7898 / ui.debug) "http://demo.signalk.org/admin/index.bundle.js:19: ReferenceError: Can't find variable: Set"
So the Kobo browser takes offense to the JavaScript on that site... and going to
https://developer.mozilla.org/en-US/...al_Objects/Set also doesn't work one bit on the Kobo
Basically it's not a good idea to run heavy javascripts browser apps. Keep it simple