[CSS] how do I calculate the subtraction of two color?

Hello! I'm trying to understand how a color has been obtained by merging two other colors, for instance:

 css

    
--color1: #02c390;
--color2: #31363B;

--result: #24544C;

  

I would like to create --result by merging the two other colors, but I don't know the percentage. I tried using color-mix but I didn't get any close results. how can I get the percentage of the two colors needed to obtain the result?

thanks in advance!