If you decide to use the tutorial, I highly recommend the new one at learn.svelte.dev over the older one at svelte.dev/tutorial. It includes more material on top of being more up-to-date.
And it has a vim mode if you pass "?vim=true" to the url.
Why not a button, I don't know but it's nice to have since Firenvim wasn't playing along with CodeMirror
