fix: move theme class to root node to prevent white flash (#392)

Alexander Sohn

18.46.2022 c36e1d8fff70ab6a817e00aa053b996342554681

 exampleSite/resources/_gen/assets/scss/scss/anatole.scss_dcc8b7002348ef29d44bd1c4b6ae0aca.json

@@ -1 +1 @@
{"Target":"scss/main.min.b2e0cb07595e3519ab1193bb421914e06c0e26b0cc561fef23b3c6131d4d2ffa.css","MediaType":"text/css","Data":{"Integrity":"sha256-suDLB1leNRmrEZO7QhkU4GwOJrDMVh/vI7PGEx1NL/o="}}
{"Target":"scss/main.min.5794be192d21535bdd301561e043a96b6adbad2b5c08279deff459e4661c613f.css","MediaType":"text/css","Data":{"Integrity":"sha256-V5S+GS0hU1vdMBVh4EOpa2rbrStcCCed7/RZ5GYcYT8="}}