Why do some css files add @ CHARSET "UTF-8" to the header?

my question is shown in the title.

Why add @ CHARSET "UTF-8" ?

what happens if you don"t add it?

Css
Jun.24,2021

forces browsers to read according to UTF-8.

it's not a big problem if you don't add it. Now it's basically UTF-8, and it's also the default.

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