The CSS code is working, I just checked your site, it is active: https://i.imgur.com/wexJezy.png
Make sure to clear all layers of cache, including browser, site, server, CDN etc..
And is it possible to call a class by the first char a user has typed?
Can you please be more specific about this? Where do you want to add this class, which element? Do you want to add it to an element whenever at least 1 character was entered?
It is possible I guess, but only with a custom script. But I need to know which element is affected.
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