How do I customize the default offline page, not just entering the body text, but its css file?

Question

I noticed many of the themes that can be downloaded via the 'Find theme' option, don't have an offline page, so, e107 defaults to its own offline page with has the 'The Voux' logo and a white background, where is that default page?  Or does it use a css file?  If so, then where is the css file or e107's default offline page so that I can customize it to add a new logo and background?

I know how to edit the contents via 'Tools->Maintenance', but other than that there are no other options to fully customize the offline page.

Answer 1

I am sure that there is info about version

 

Answer 2

When you don't know what template (or if is there template at all), just open file and look for word "template"

In your case - file sitedown.php and result:  

So it should be template-able.   You should copy core template to your theme. Don't forget to check if

$SITEDOWN_TABLE is not defined somewhere in theme (or anywhere)