How to change favicon icon color?

[alexUnd]

Hi. I am not strong in css, but I have customized everything for myself, using the instructions to TST. but one setting that I would like to implement, I can not do anything.
I would like to paint another color icons (favicons) of specific service tabs. I have reviewed all the possible instructions, but my code doesn't do what I want it to do.
I've tried something like this, but "fill" doesn't work.

tab-item[data-current-uri^="about:"] tab-favicon { fill: rgb(212,34,34) !important; }

would appreciate any help

[irvinm]

How about this?

tab-item[data-current-uri^="about:"] tab-favicon { 
    filter: brightness(0) saturate(100%) invert(18%) sepia(48%) saturate(5054%) hue-rotate(351deg) brightness(103%) contrast(89%); 
}

[alexUnd]

Thank you! with changing "hue-rotate" parameter in this code i can match any color!