Page background issue (when we were off line) - help to understand please

Using OC 2.0.3.1
Had customers calling saying the store had problems.
Overnight when we were off line the background went from moss green to white !!!
What happened - OC issue?
Result the boxes and text couldn't be seen except by highlighting the page. See *www.hkab.co.uk/store*...........
We do nothing more advanced that listing and category management usually adding items.
Wouldn't dare try tweek anything.
Q? Can someone give me a step by step, menu by menu, to the section where I "should I hope" be able to reset the colour.
All help much appreciated

Where and how is the background image placed in the code or was it solid colour.
The background colour is set to transparent !
I can find no background image in the code for the header.
It is journal theme - so probably related to journal problem.
I would say something in your css for header is messed up

Journal issue contact them. https://www.hkab.co.uk/store/index.php? ... &j2v=2.6.4

My apology
I meant to say background colour.
The weird thing is it happened overnight all of its own accord i.e. we didn't do anything.
In fact I think it was 2 weeks or so back we only added 1 item. That was the last ting we did.

Your host may have updated PHP so reach out to them or contact Journal. The problem is error output in your css file.