"want more email subscribers?" it using Action Page Lead with adding some css on child theme.
for button action, i think popup with email form will be great than sending people to another landing page.
for me, MD is great but right now people prefer using Live Building (Drag n Drop) where is more easier than touching code.
Ideas for MD
MD has built in MD Class Helper https://marketersdelight.net/styles/
but for someone, it's difficult to remembering all css class of MD.
in my opinion, it's better to build shortcode or create MD Class helper include in Wordpress editor â€¦
so people more easier to styling post with MD Class