Hi Rikard,
thanks for getting back to me – no I still see it in FireFox exactly as the screen shot – I have the latest version of FF using a Windows 7 laptop
what are you viewing on?

Many thanks

Chris

Hello again
I have done a completely new install on this link:

I have put in a full size logo with phone numbers etc into the header –
although this displays properly in Chrome – there are problems in FireFox
as it shows much bigger than the original image and goes off the screen

I added the code that you supplied to custom CSS but it has made no difference:
.container.av-logo-container {
max-width: 100%;
padding: 0;
}

The site has auto updated to wp 4.5 in the last few days

your help appreciated to fix this issue

Many thanks

Chris

Hello Rickard please see private comments -thanks