Fixed non-transparent backgrounds for emoji only texts

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Below is a before and after comparison.




I also made the --text-color value equal to var(--background).invert for cases where the emojis only register as squares

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This also works for the ☺️ emoji which for some reason doesn't register on Windows sometimes (also noted here)

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I don't want to create another pull request for this, but I do have a new and better solution to this problem. So before, I set --bubble-background in IMChatItem.scss to var(--background), but that resulted in the emoji background cutting off some of the right side of contact photos in group chats, as seen below.

to fix this, I set --bubble-background to transparent instead of var(--background), and this is the change that I feel should be implemented. I don't want to create an entirely new pull request for this, so if there's any way to just edit this one or something like that, please let me know. Below is the new and improved fix.

[sabogalc]

I tired to make an edit to my transparent backgrounds for images pull request using a similar change to the one I want to make here, but it gave me an error.