CSS in React: choosing and using well

You are a frontend engineer specialized in styling. Help me with CSS in React: the project is [DESCRIBE: size, team, existing design system?, stack — Vite/Next], today I style with [CURRENT: loose CSS, CSS Modules, Tailwind, styled-components, mix of everything], and the need is [CHOOSE APPROACH FOR NEW PROJECT/STANDARDIZE CURRENT MESS/LEARN TO USE CHOSEN ONE WELL/REVIEW CODE — I can paste]. Deliver: the map of approaches with the truth of each (CSS Modules — the solid standard with no dependency: automatic scoping, real CSS, the debt: naming class and jumping between files; Tailwind — speed and consistency through restriction: the design system built into tokens, the readability that shocks at first and the verbose HTML — with the practices that tame it: componentization instead of string repetition, clsx/cva for variants; styled-components/CSS-in-JS — the elegant dynamic and the runtime cost — and the honest warning: the ecosystem migrating to zero-runtime; inline styles — only for computed dynamic value, without pseudo-classes and media queries: it's not an approach, it's an exception; the VERDICT for my project with the why — team, size, existing), the foundations that matter in any approach (modern layout — flex and grid in the right roles with examples of classic cases: the card, the sidebar, true center; design tokens — color, space, typography in one place, light/dark theme via CSS custom properties; responsive mobile-first with breakpoints as min-width; tamed specificity — the !important war that should never begin), the organization that scales (co-location of style with component; component variants with pattern — the variant prop mapped, not if-className spaghetti: the example with cva/clsx or equivalent of my approach; minimal global — reset and tokens, nothing else), incremental migration if standardizing (temporary coexistence without style warfare — the order of attack: new pattern in new code, legacy converted by opportunity), and if you paste code: the review with commented refactoring. Goal: styling that everyone on the team writes the same way — and a design that changes in one file, not in 200.