User blog comment:Mira Laime/New Page Header on Discussions/@comment-26923519-20170726175250/@comment-26339491-20170726180620

Wikis with a dark theme have their Discussions appear in a dark theme as well (admins can make adjustments via the Theme Designer), but we don't currently plan to add a switch for users to go back and forth between the two modes. It'd surely be nice to have, but there are other updates to Discussions that are more urgently needed at the moment.