Fix incorrect dark theme detection caused by missing css load waiting

[ShGKme]

☑️ Resolves

Sometimes with a dark theme, some components act like a light theme.

The problem appears when Talk app initializes and starts faster than CSS with the user's theme is loaded.
(Currently, Talk detect dark theme by CSS)

loadCss util is supposed to be async and return a promise, but actually, it doesn't.

This could be not the only problem with dark theme detection thus it also appears out of initial loading.

🖼️ Screenshots

🏚️ Before	🏡 After

🚧 Tasks

• Create and return promise in loadCss util

[Antreesy]

Package seems to work proper, and an error with named import dissapeared, but npm start goes into infinite loading for me

[ShGKme]

Package seems to work proper, and an error with named import dissapeared, but npm start goes into infinite loading for me

Any errors in the console?

[nickvergessen]

Right	same here

[ShGKme]

Ready to review again after fixing the mentioned issue.