Flexbox website guide

I’m creating an email course. It is a guide to use Flexbox in website layout. It’s free. It’s content is based on Flexbox.website, but I will have bonus/update content in the email course.

p.s. This is my first try of hosting email course on ConvertKit. Don’t know if it fits my usage eventually. But I’ll give it a try and report here later on how I use it.