What we could do is move these colors to CSS custom properties instead of setting them inline, which would make the colors easily accessible in any CSS/SCSS. I don’t know when we’ll be able to get to that, but I’ll keep it on my list of to-dos.
That would be awesome
BTW is there any other way to achieve the view I want?
I’ve read that I can override templates for specific parts of Discourse, which template file I must override and how should I do that in my custom theme?
Note that I’ve applied the style directly to the h3 element of the title because it is a direct child from the td in which the inline style was applied. So if the template ever get rid of it you will have to tweak your CSS.
But you can skip overriding the components/parent-category-row as you wanted.