Adding a CA certificate (or: solving connection not private/invalid certificate authority error)

If you get an error on any of our (usually internal) webppages about a certificate not being trusted, follow the following steps to download and add our CA (certificate authority) certificate to your browser to trust it. Make sure you only do this for trusted websites/certificate authorities (you can trust us on our endearing character and beautiful eyes), and make sure you download the correct CA certificate.