https://marp.app/blog/how-to-make-custom-transition
Other examples: Transition showcase / Morphing animation
gate
https://glitch.com/edit/#!/marp-cli-page-transitions?path=scss/transitions/_gate.scss
gate-tilted
https://glitch.com/edit/#!/marp-cli-page-transitions?path=scss/transitions/_gate-tilted.scss
revolve
https://glitch.com/edit/#!/marp-cli-page-transitions?path=scss/transitions/_revolve.scss
stripe
https://glitch.com/edit/#!/marp-cli-page-transitions?path=scss/transitions/_stripe.scss
curtain
https://glitch.com/edit/#!/marp-cli-page-transitions?path=scss/transitions/_curtain.scss