Make Safari accept an untrusted certificate
I'm using Safari 10.0.1 on macOS Sierra 10.12.1
I'm trying to view use Safari to view a web server I use for staging content. Since it's only a staging server, I have a certificate with an untrusted root (it's from the letsencrypt staging environment). It used to be that when I tried to load a site like this from Safari, it would alert me, but I could still accept the insecure certificate and continue on to the site.
Lately, I just get an error that "Safari can't establish a secure connection to the server," and that's it. There's no option to load it anyway. There's no lock icon in the URL bar to look at the certificate. I've been using Chrome to load this site because it has the behavior I used to see in Safari. Is there any way to get the old behavior back?
Thanks
MacBook Pro with Retina display, macOS Sierra (10.12.1)