Is there any way on the client side to pin the certificate you are expecting a website to be served under ? I use SimpleNote a lot, and don't want my work snoo

Is there any way on the client side to pin the certificate you are expecting a website to be served under ? I use SimpleNote a lot, and don't want my work snooping on the contents. Nothing dodgy, just a little tin-foil hatty. If they do snoop, and I have no mechanism to know when they are, then I'll stop using it. So SimpleNote use a Comodo certificate ( by inspection ). How can I personally instruct my browser to reject any cert from a different provider just for SimpleNote.com ?