The SSL Adventures of Heidi's Website: A Tale of Old and New Browsers

Hello to the folks whose services exist outside the mundane world of technology: this post is for you.
This is extra important if you have a business website.
We're going to explore an interesting situation that happened to one of my clients, Heidi.
Heidi has a Holistic Wellness business specializing in Biofield Tuning and I helped her set up her Wix website. You can learn more about Heidi's business here.
Yesterday, one of Heidi's clients faced an SSL error while visiting her website. But don't worry, Heidi's website has a valid SSL certificate!

So, what was the issue?
Let's dive in and learn about this tale of old and new browsers, SSL certificates, and how they impact our online experience.