Styling the result list, file type icons

I managed to get different icons displaying dependent on which type of result comes up, thanks to @gminero :)

Now I want to style them - when I say style I just want to change the colour to match our corporate brand. I read here: https://docs.coveo.com/en/292/javascript-search-framework/customizing-svg-icons that this may be able to be done through css so checked out the console in Chrome and changed the colours there, however, when I add the css to my custom css sheet in Salesforce's Community Builder, it has no effect! I'm assuming I'm missing something, somewhere.

Original:

Target:

An example, I added the lines:

.coveo-sprites-salesforce-standard-post {
    background-color: #00a7ce;
}