I would recommend Fomantic UI https://fomantic-ui.com/ https://fomantic-ui.com/ (active community fork of Semantic UI) + Semantic UI React https://react.semanti

I would recommend Fomantic UI https://fomantic-ui.com/ https://fomantic-ui.com/ (active community fork of Semantic UI) + Semantic UI React https://react.semantic-ui.com/ https://react.semantic-ui.com/ (which is a React wrapper over Semantic UI, but works with Fomantic UI as well). Almost no CSS writing is necessary, customizability of the React components via props should be enough for MVP and even further.