HoloWorld, on the level of a civilization, is color blind and doesn't give any advantage or disadvantage to anybody based on the color of their skin. Or based on just about anything else. It is an even playing field, with fundamental principles in place to hinder that anybody would make it otherwise.
Individuals and communities and businesses are free to make choices based on race, if that is what they prefer to do, just like they can arrange their affairs based on any other criteria they feel like. So, there is nothing to hinder that somebody makes a bar that is only for Chinese people, or a church that is only for black people, or a school that is only for white people.
That will not be very typical, and probably won't be particularly popular. Most people will live by the general HoloWorld principles of harmony and openness and celebration of diversity.
Racial tension often develops from monopolies being controlled with a racial bias, or from individuals with racial biases being forced to live under conditions they wouldn't prefer. That is, if there is only one school system and it is made by and favors white people, then naturally resentment can build up from those who aren't favored by it. Or, if Joe Schmoe has irrational fears about black people, but he is forced to work with some, that will create tension.
So, the principle is to give people what they want in terms of their own lives. If somebody wants to live in an all-white, gated community, where everybody's a Presbyterian, or everybody's wearing golf shoes -- go right ahead, they are free to do that. They can set their own rules and set up any rules for admission or membership to their community. They are free to say: "We don't want any kids, we don't want any black people, we don't want anybody in bare feet, we don't want any pagans, we don't want anybody who smokes, we don't want any longhaired men". They are free to do that, as long as it is clear to any prospective visitors what the rules are. And as long as they don't go around trying to force others to live by those rules.
Notice the direction of things. Anybody who wants to set up very limiting moral rules, or who have very specific biases on who they don't want to deal with, or who they don't like -- they will automatically isolate themselves somewhat from the rest of society. That might be beneficial in that it allows them to form a community with other likeminded people, and that it keeps them from rubbing their biases against other people who disagree strongly with them, or who are at the receiving end of their biases.
The principles that are free to spread widely and globally are those of tolerance of diversity, cooperation, communication, unity, love, enjoyment, celebration, help, support, learning, networking, inclusion.
It is fairly logical, really. Attitudes of exclusion will naturally exclude those who have them from a bigger scheme of things. By choosing very specifically what they want and what they don't want, they will create a limited bubble of existence that has/hasn't those elements. So, exclusion means contraction into a zone of comfort.
Attitudes of inclusion will naturally try to encompass a bigger and bigger portion of what is going on in the world. Becoming more exposed to diversity, being more open to surprises, being ready to learn from those who are different.
HoloWorld itself is an inclusionary space. No global biases that excludes anybody with specific preferences. Those with specific preferences will simply group themselves together and will probably cultivate their uniqueness and maybe police it against intrusion. All of that is fine and is from HoloWorld's perspective simply the many diversified modes of living being included in the overall umbrella of a civilization.
The overall approach here to diversity of any kind, including skin color and culture, is NOT to even everything out and aim for an average of everything that is there. The ideal is certainly not that we all have the same grey skin, are androgenous, and have the same income and intelligence.
There is no affirmative action or any other uniform attempts of rectifying any perceived past injustices against certain groups, or of adjusting statistical imbalances between different groups.
If black kids are statistically a little more likely to want to play basketball than to study geometry, as compared to oriental kids -- so what -- there is nothing less valuable at being good at basketball as compared to geometry, so there is no reason to force an equal percentage of all races to be studying geometry.
Diversity creates energy, it makes life interesting, it gives us new things to learn all the time, and it gives us choice in life.