mail theme should follow personal site theme settings

[mcnesium]

When the site theme in a user's profile is e.g. set to "Mastodon (light)", the (HTML-)mail notifications should be themed the same way to have a consistent user experience.

[jazmichaelking]

Agreed, and if styling is an issue, at a minimum send the mail in text only if theme = Mastodon (light). As admin of a custom theme instance, these E-mails are quite jarring for the newer members, they have never participated with a dark "Mastodon" - instead they were expecting a light themed "toot.wales" message. We have a relatively less techy audience.