Themes not working

[n1ght-watch]

While on cs50.dev I tried to change the theme in order to help alleviate the strain on my eyes however whenever I tried to change the theme, it wouldn't let me as it just stuck to one

Version: 1.106.3
Commit: bf9252a
User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/26.1 Safari/605.1.15
Embedder: codespaces