Every year, Hollywood inevitably comes under criticism for its lack of racial diversity. But another lesser-known yet still pervasive problem also resurfaces: the lack of diversity in skin tone. It happened again with “In the Heights,” a film that was called out this week for its dearth of dark-skinned, Black Latinos in leading roles. Colorism — or discrimination against darker-skinned people within their same ethnic group — lurks deep among pretty much all communities with varying levels of melanin. But it doesn’t get talked about, and experts say this is detrimental to the fight for racial justice for all people of color.