Jquery - Copy HTML to clipboard

I've created an email signature generator for one of my clients. The generator can be viewed here: https://www.ouryclark.com/signature/Signature-Generator.html

As you'll see from the Signature-Generator.html file the form populates the signature on the right-hand side. What I need help with is to copy the HTML from the preview so my client can easily paste it into their email software.

I'm currently using Jquery so keeping in this framework is required.