I was just wondering the easiest way to start a custom theme in the new update, now that everything is stored in page.theme and not in a .txt document I've been having trouble editing or creating a theme based off of elemental.

If someone could guide me through the steps of doing this that would be awesome. I'm trying to tweak the CSS slightly more than the editor will allow through the customize section of the dashboard and I'd like a little bit more control over things.

Apologies for being a bother, again!