- The whole site *works* via HTTPS, provided you use secure.byond.com (which is redirected to from https://www.byond.com, but interestingly not from https://byond.com
- Every link on a page loaded via HTTPS will just take you back to an HTTP page.
- secure.byond.com is just a CNAME for byond.com
The forum *should* be usable over SSL; the certificate you're using is a wildcard already, so you wouldn't need another cert for www.byond.com, and your webserver can already serve pages over HTTPS; the only issue is that every link is explicitly set to use the HTTP protocol instead of HTTPS;
For example, the "Forums" link, right at the top, is
<a class="mainmenu" href="http://www.byond.com/forum/"><span class=menu_center></span><span>Forums</span></a>
when it should be
<a class="mainmenu" href="/forum/"><span class=menu_center></span><span>Forums</span></a>
Ideally the whole site would be accessible via SSL, without having to edit the URL every time you loaded a page.