Hi Keith, the background colors disappear and get replaced by your preferred color (green, in your case) when you disable sites from using their own colors. That's the setting I was referring to.

Thanks for reply.

I have allowed sites to choose their own colours.

There is still no change and I think I will go through all the suggestions again just to check I have not missed anything.

I can always use Chrome if I need perfect web pages in the meantime.

Thanks for all the help given and I will report back in about a week.

I am attaching a file showing how web pages sometimes look (again not in Chrome). They appear out of focus and this does not change whether enlarged or reduced in size. Does this relate to my main problem and does it offer any clues?

Hi Keith, awesome example. That page actually is a PDF being displayed by Firefox's built-in PDF viewer. The viewer deconstructs PDFs into their component bits and regenerates them as web content. Clearly something is going wrong with that one.

The built-in viewer is not as mature as Adobe's Acrobat PDF viewer. You may need to switch back. This article has the steps: View PDF files using Firefox’s built-in viewer.

Many thanks for help. I did not realize that Firefox had a PDF viewer which had over-ridden my preferred choice of Adobe.

I followed your instructions and all is now well.

I still have my overriding problem with incomplete / strange website images.

I discovered that Internet Explorer (which I seldom use and have never adjusted) also did not display properly, therefore suggesting that there was no problem with my Firefox settings.

I replaced my windows page with the normal windows logo screen and everything now displays as it should.

I had changes this screen previously but must have chosen a high contrast setting.

All problems now solved so many thanks for all help received.