Sponsors are listed by tier in a sub directory -- tier name order and colour are set in their _index.md. We need a custom template to display this how we want (pages by section, sorted by weight) -- transparent mixes up subpage order.
Sponsor images are located next to their .md file with the same name -- .png only instead of .md. Note when adding new images, these should be transparent around the logo -- both so light/dark mode looks good, and so the silhouette effect works properly.
If you want to add a new tier, add a new directory, copy in a _index.md and change the weights to sort them properly.
25/26 Update: If you'd like a Bronze Sponsor to appear on the frontpage of the site, go to that sponsor's page and set extra.frontpage to true