--- id: wiki-2026-0508-dynamic-theming title: Dynamic Theming category: 10_Wiki/Topics status: verified canonical_id: self aliases: [Theming, Dark Mode, CSS Variables Theming] duplicate_of: none source_trust_level: A confidence_score: 0.9 verification_status: applied tags: [frontend, css, theming, design-system] raw_sources: [] last_reinforced: 2026-05-10 github_commit: pending tech_stack: language: TypeScript framework: React --- # Dynamic Theming ## 매 한 줄 > **"매 design token 을 runtime swap 할 수 있는 architecture"**. CSS custom properties (variables) 가 매 modern theming 의 backbone 이며, JS bundle 의 무관 하게 instant theme switching 의 가능. 2026 의 light/dark/high-contrast/brand-variant 의 매 standard. ## 매 핵심 ### 매 3-layer token 구조 - **Primitive tokens**: raw values (`--blue-500: #3B82F6`). - **Semantic tokens**: intent-based (`--color-primary: var(--blue-500)`). - **Component tokens**: scope-specific (`--button-bg: var(--color-primary)`). ### 매 swap 메커니즘 - `data-theme="dark"` 속성 의 `` element 의 set. - CSS 의 `[data-theme="dark"] { --color-bg: #0a0a0a }` 의 override. - 매 zero JS re-render — 매 paint cycle 만 trigger. ### 매 응용 1. Light/dark mode toggle. 2. Brand white-labeling (multi-tenant SaaS). 3. Accessibility (high-contrast, reduced-motion variant). 4. Per-user customization (saved theme preference). ## 💻 패턴 ### Token 정의 (CSS) ```css :root { /* Primitive */ --blue-500: #3B82F6; --gray-900: #111827; --gray-50: #F9FAFB; /* Semantic — light default */ --color-bg: var(--gray-50); --color-fg: var(--gray-900); --color-primary: var(--blue-500); } [data-theme="dark"] { --color-bg: var(--gray-900); --color-fg: var(--gray-50); } [data-theme="high-contrast"] { --color-bg: #000; --color-fg: #fff; --color-primary: #ffff00; } ``` ### Theme provider (React 19) ```tsx import { createContext, use, useEffect, useState } from "react"; type Theme = "light" | "dark" | "system"; const ThemeCtx = createContext<{ theme: Theme; set: (t: Theme) => void }>(null!); export function ThemeProvider({ children }: { children: React.ReactNode }) { const [theme, setTheme] = useState( () => (localStorage.getItem("theme") as Theme) ?? "system" ); useEffect(() => { const resolved = theme === "system" ? matchMedia("(prefers-color-scheme: dark)").matches ? "dark" : "light" : theme; document.documentElement.dataset.theme = resolved; localStorage.setItem("theme", theme); }, [theme]); return {children}; } export const useTheme = () => use(ThemeCtx); ``` ### FOUC 방지 (inline script) ```html ``` ### Tailwind 4 의 통합 ```css @import "tailwindcss"; @theme { --color-bg: var(--bg); --color-fg: var(--fg); } :root { --bg: #fff; --fg: #111; } [data-theme="dark"] { --bg: #0a0a0a; --fg: #f5f5f5; } ``` ```tsx

매 theme-aware

``` ### System preference 의 listen ```ts const mq = matchMedia("(prefers-color-scheme: dark)"); mq.addEventListener("change", (e) => { if (localStorage.getItem("theme") === "system") { document.documentElement.dataset.theme = e.matches ? "dark" : "light"; } }); ``` ### View Transitions API (smooth swap) ```ts function toggleTheme() { if (!document.startViewTransition) { flipTheme(); return; } document.startViewTransition(() => flipTheme()); } ``` ```css ::view-transition-old(root), ::view-transition-new(root) { animation-duration: 250ms; } ``` ### Brand variant (multi-tenant) ```css [data-brand="acme"] { --color-primary: #FF6B35; } [data-brand="globex"] { --color-primary: #2EB872; } ``` ## 매 결정 기준 | 상황 | Approach | |---|---| | Static site / blog | CSS variable + `data-theme` | | SaaS multi-tenant | CSS variable + brand attribute layer | | RN / Native | Theme context + StyleSheet (no CSS vars) | | Tailwind 의 사용 | Tailwind 4 `@theme` + CSS variable | | Email template | Inline styles + `prefers-color-scheme` media query | **기본값**: CSS custom properties + `data-theme` attribute + inline FOUC script. ## 🔗 Graph - 부모: [[CSS_Architecture_and_Styling|CSS Architecture]] · [[Design Tokens]] - 변형: [[Tailwind CSS 4]] · [[CSS_Architecture_and_Styling|CSS-in-JS]] - 응용: [[Dark Mode]] · [[Accessibility (a11y)]] - Adjacent: [[View Transitions API]] ## 🤖 LLM 활용 **언제**: design token system 의 설계, dark mode 구현, multi-brand theming. **언제 X**: simple 의 single-color brand 의 — 매 over-engineering. ## ❌ 안티패턴 - **JS-only theme**: setState 의 모든 component re-render — 매 slow 의. - **Hard-coded color in component**: token 의 bypass — 매 swap 불가능. - **No FOUC script**: hydration 전 wrong theme flash — 매 jarring UX. - **Theme 의 localStorage 의만 의존**: SSR 의 server-render mismatch. ## 🧪 검증 / 중복 - Verified (MDN, web.dev, Tailwind CSS docs, Adobe Spectrum 의 token system). - 신뢰도 A. ## 🕓 Changelog | 날짜 | 변경 | |---|---| | 2026-05-08 | Phase 1 | | 2026-05-10 | Manual cleanup — 3-layer token + FOUC + View Transitions 추가 |