Set theme in UI section of appsettings.json:
"UI": {
"Theme": "default",
of via enviroment-file vars or compose-file:
- UI_Theme: default
Themes:
ceruleancosmocyborgdarklydefaultflatlyjournalliteralumenluxmateriamintypulsesandstonesimplexsketchyslatesolarspacelabsuperherounitedyeti
You cah check live demos at official https://bootswatch.com/ site.