WordPress in Firefox for Android – Error

I am getting strange displays occurring in Firefox for Android. On Android Chrome and on Chrome and Firefox on Windows the site is working fine – no problems.

But on Firefox for Android I get an erroneous background image on the home page (individual article pages seem to work fine).

I have am working on a child theme for my site, but this may or may not be related to that. I have created a custom background using a radial gradient, so this may or may not be the issue (it works fine on posts pages, so perhaps not the issue)?

Here is my site: Church Peace

And here is a screenshot of the home page on Android Firefox: Dropbox image

Many thanks for your help in advance!

Mark.