Hi!!! I am new to using Gluestack and Nativewind... actually I have been trying to apply some stylings to the elements... however, I struggle to understand how things actually work... coz some of the colors work while others dont... for instance..

export default function AboutPage() {
    return (
        <Box className="p-2 m-3 bg-background-0 h-full">
            <Heading size="3xl" className="color-white">
                About Us
            </Heading>
        </Box>
    );
}

if I add bg-gray-900 it works while bg-background-0 wont work... why does that happen...

I am using the default themes... I do see its got something to do with tokens but am not sure how to set them up as I find it hard to follow the documentation given... It would be really helpful if anyone can explain this to me abit