Download the iguide link for use offline

any idea why walls show this way on offline version?

Its probably because you are using Firefox.
Use chrome and that should be fixed.

When I use chrome, index file type is still Firefox HTML document. Don’t know how to change it so I can use chrome

The reason is because your default browser is Firefox which you can change that following the link below:
https://support.google.com/chrome/answer/95417?co=GENIE.Platform%3DAndroid&hl=en

OR

after opening the tour in the Firefox, copy the URL from your Firefox and paste it into Chrome. That should work.