I tend to start a project by making a classless stylesheet of sorts to set a baseline for the theme and branding.

Its almost never all you need for an actual project, but it is a nice starting point to get the basics in place.

I find that I look at the endless list of classless stylesheets shared online as a starting point, most have at least one or two interesting tricks worth borrowing. I don't find using the off the shelf ones particularly useful though, it ends up with a very generic look to it like the old default bootstrap site or newer default tailwind site.