I'd like to make some pages that retain the header forum wrapper, and am trying to find out how I can do this.
Hello lostmonk and welcome! :)
This file has most of what you'd need:
https://github.com/elkarte/elkarte.net/blob/4f34bc6f33485215f7c2ccdcae18c2ed6d37a545/elk/home.php
In particular:
https://github.com/elkarte/elkarte.net/blob/4f34bc6f33485215f7c2ccdcae18c2ed6d37a545/elk/home.php#L2
gives everything up to the... upper linktree/breadcrumb I think (my memory always messes up where it ends).
a couple of lines to set up "general" stuff if you need it, then:
https://github.com/elkarte/elkarte.net/blob/4f34bc6f33485215f7c2ccdcae18c2ed6d37a545/elk/home.php#L8
grabs SSI.php (of course use the correct path to your SSI).
Add your content.
And finally:
https://github.com/elkarte/elkarte.net/blob/4f34bc6f33485215f7c2ccdcae18c2ed6d37a545/elk/home.php#L111
show the page.
HTH! ;D