diff --git a/frontend/src/components/Footer.jsx b/frontend/src/components/Footer.jsx
index 5712197..a2c9bb6 100644
--- a/frontend/src/components/Footer.jsx
+++ b/frontend/src/components/Footer.jsx
@@ -1,18 +1,24 @@
 export default function Footer() {
   return (
-    <footer className="border-t border-white/5 mt-16">
+    <footer
+      className="border-t mt-16 transition-colors duration-300"
+      style={{ borderColor: 'var(--header-border)' }}
+    >
       <div className="mx-auto max-w-5xl px-6 py-8 space-y-4">
         <div className="flex items-center gap-2.5">
           <img src="/favicon.ico" alt="" className="w-6 h-6" />
           <span className="font-bold text-sm">메이플스토리 유틸리티</span>
         </div>
 
-        <div className="grid gap-2 sm:grid-cols-2 text-xs text-gray-500">
+        <div
+          className="grid gap-2 sm:grid-cols-2 text-xs transition-colors duration-300"
+          style={{ color: 'var(--text-dim)' }}
+        >
           <div className="space-y-1">
             <p>This site is not associated with NEXON Korea.</p>
             <p>
               Data based on{' '}
-              <a href="https://openapi.nexon.com" target="_blank" rel="noopener noreferrer" className="text-emerald-400/80 hover:text-emerald-300 transition">
+              <a href="https://openapi.nexon.com" target="_blank" rel="noopener noreferrer" className="text-emerald-500 hover:text-emerald-400 transition">
                 NEXON Open API
               </a>
               .
diff --git a/frontend/src/components/Layout.jsx b/frontend/src/components/Layout.jsx
index 6fe4405..730e785 100644
--- a/frontend/src/components/Layout.jsx
+++ b/frontend/src/components/Layout.jsx
@@ -3,6 +3,7 @@ import { Outlet, Link, useLocation, useMatch } from 'react-router-dom'
 import { useQuery } from '@tanstack/react-query'
 import { api } from '../api/client'
 import Footer from './Footer'
+import { useThemeStore } from '../stores/theme'
 
 const SITE_NAME = '메이플스토리 유틸리티'
 
@@ -40,29 +41,100 @@ function CurrentMenuTitle() {
   if (!menu) return null
 
   return (
-    <div className="flex items-center gap-3 text-gray-400">
-      <span className="text-white/20">/</span>
+    <div
+      className="flex items-center gap-3 transition-colors duration-300"
+      style={{ color: 'var(--text-muted)' }}
+    >
+      <span style={{ color: 'var(--text-slash)' }}>/</span>
       <div className="flex items-center gap-2">
         {menu.image?.url && (
           <img src={menu.image.url} alt="" className="w-5 h-5 object-contain" />
         )}
-        <span className="text-sm font-medium text-gray-200">{menu.title}</span>
+        <span
+          className="text-sm font-medium transition-colors duration-300"
+          style={{ color: 'var(--text-emphasis)' }}
+        >
+          {menu.title}
+        </span>
       </div>
     </div>
   )
 }
 
+function ThemeToggle() {
+  const theme = useThemeStore((s) => s.theme)
+  const toggleTheme = useThemeStore((s) => s.toggleTheme)
+  const isLight = theme === 'light'
+
+  const handleToggle = () => {
+    if (typeof document !== 'undefined' && document.startViewTransition) {
+      document.startViewTransition(() => toggleTheme())
+    } else {
+      toggleTheme()
+    }
+  }
+
+  return (
+    <button
+      type="button"
+      onClick={handleToggle}
+      aria-label={isLight ? '다크 모드로 전환' : '라이트 모드로 전환'}
+      title={isLight ? '다크 모드' : '라이트 모드'}
+      className="relative inline-flex h-8 w-14 items-center rounded-full border transition-colors duration-300 hover:border-emerald-500/40"
+      style={{
+        background: 'var(--toggle-bg)',
+        borderColor: 'var(--toggle-border)',
+      }}
+    >
+      <span
+        className="absolute left-1 top-1 flex h-6 w-6 items-center justify-center rounded-full shadow-md transition-[transform,background] duration-300 ease-out"
+        style={{
+          transform: isLight ? 'translateX(24px)' : 'translateX(0px)',
+          backgroundImage: 'linear-gradient(to bottom right, var(--toggle-thumb-from), var(--toggle-thumb-to))',
+          color: 'var(--toggle-thumb-icon)',
+        }}
+      >
+        {isLight ? (
+          <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 20 20" fill="currentColor" className="h-3.5 w-3.5">
+            <path fillRule="evenodd" d="M10 2a.75.75 0 01.75.75v1.5a.75.75 0 01-1.5 0v-1.5A.75.75 0 0110 2zM10 15a.75.75 0 01.75.75v1.5a.75.75 0 01-1.5 0v-1.5A.75.75 0 0110 15zM18 10a.75.75 0 01-.75.75h-1.5a.75.75 0 010-1.5h1.5A.75.75 0 0118 10zM5 10a.75.75 0 01-.75.75h-1.5a.75.75 0 010-1.5h1.5A.75.75 0 015 10zM15.657 4.343a.75.75 0 010 1.06l-1.06 1.061a.75.75 0 11-1.061-1.06l1.06-1.061a.75.75 0 011.061 0zM6.464 13.536a.75.75 0 010 1.06l-1.06 1.061a.75.75 0 01-1.061-1.06l1.06-1.061a.75.75 0 011.061 0zM15.657 15.657a.75.75 0 01-1.06 0l-1.061-1.06a.75.75 0 011.06-1.061l1.061 1.06a.75.75 0 010 1.061zM6.464 6.464a.75.75 0 01-1.06 0L4.343 5.404a.75.75 0 011.06-1.06l1.061 1.06a.75.75 0 010 1.06zM10 6a4 4 0 100 8 4 4 0 000-8z" clipRule="evenodd" />
+          </svg>
+        ) : (
+          <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 20 20" fill="currentColor" className="h-3.5 w-3.5">
+            <path fillRule="evenodd" d="M7.455 2.004a.75.75 0 01.26.77 7 7 0 009.958 7.967.75.75 0 011.067.853A8.5 8.5 0 116.647 1.921a.75.75 0 01.808.083z" clipRule="evenodd" />
+          </svg>
+        )}
+      </span>
+    </button>
+  )
+}
+
 export default function Layout() {
   const [fullscreen, setFullscreen] = useState(false)
   const isAdmin = !!useMatch('/admin/*')
   const homeTo = isAdmin ? '/admin' : '/'
+  const theme = useThemeStore((s) => s.theme)
+
+  useEffect(() => {
+    const root = document.documentElement
+    if (theme === 'light') root.setAttribute('data-theme', 'light')
+    else root.removeAttribute('data-theme')
+  }, [theme])
 
   return (
     <LayoutContext.Provider value={{ fullscreen, setFullscreen }}>
-      <div className={`min-w-[1280px] text-white flex flex-col ${
-        fullscreen ? 'h-dvh' : 'min-h-screen'
-      }`}>
-        <header className="sticky top-0 z-20 border-b border-white/5 bg-gray-950/80 backdrop-blur-md shrink-0">
+      <div
+        className={`min-w-[1280px] flex flex-col transition-colors duration-300 ${
+          fullscreen ? 'h-dvh' : 'min-h-screen'
+        }`}
+        style={{ color: 'var(--text-strong)' }}
+      >
+        <header
+          className="sticky top-0 z-20 border-b backdrop-blur-md shrink-0 transition-colors duration-300"
+          style={{
+            background: 'var(--header-bg)',
+            borderColor: 'var(--header-border)',
+          }}
+        >
           <div className="mx-auto flex max-w-[1400px] items-center justify-between px-6 py-4">
             <div className="flex items-center gap-3">
               <Link to={homeTo} className="group flex items-center gap-2.5">
@@ -73,6 +145,7 @@ export default function Layout() {
               </Link>
               <CurrentMenuTitle />
             </div>
+            <ThemeToggle />
           </div>
         </header>
         <main className={`flex-1 mx-auto w-full max-w-[1400px] ${
diff --git a/frontend/src/index.css b/frontend/src/index.css
index 2766bd4..18107a4 100644
--- a/frontend/src/index.css
+++ b/frontend/src/index.css
@@ -6,11 +6,64 @@
   --font-maple: "Maplestory", "Noto Sans KR", sans-serif;
 }
 
+/* 테마 토큰 - dark (default) */
+:root {
+  color-scheme: dark;
+  --bg-from: #030712;
+  --bg-via: #030712;
+  --bg-to: #0f172a;
+  --scrollbar-thumb: rgba(255, 255, 255, 0.12);
+  --scrollbar-thumb-hover: rgba(255, 255, 255, 0.22);
+  --scrollbar-track: transparent;
+
+  --header-bg: rgba(3, 7, 18, 0.8);
+  --header-border: rgba(255, 255, 255, 0.05);
+
+  --text-strong: #ffffff;
+  --text-emphasis: #e5e7eb;
+  --text-muted: #9ca3af;
+  --text-dim: #6b7280;
+  --text-slash: rgba(255, 255, 255, 0.2);
+
+  --toggle-bg: rgba(17, 24, 39, 0.6);
+  --toggle-border: rgba(255, 255, 255, 0.1);
+  --toggle-thumb-from: #e5e7eb;
+  --toggle-thumb-to: #9ca3af;
+  --toggle-thumb-icon: #0f172a;
+}
+
+/* 테마 토큰 - light */
+[data-theme="light"] {
+  color-scheme: light;
+  --bg-from: #ffffff;
+  --bg-via: #ffffff;
+  --bg-to: #ffffff;
+  --scrollbar-thumb: #a0a0a0;
+  --scrollbar-thumb-hover: #707070;
+  --scrollbar-track: transparent;
+
+  --header-bg: rgba(255, 255, 255, 0.8);
+  --header-border: rgba(0, 0, 0, 0.08);
+
+  --text-strong: #0f172a;
+  --text-emphasis: #1f2937;
+  --text-muted: #475569;
+  --text-dim: #64748b;
+  --text-slash: rgba(0, 0, 0, 0.2);
+
+  --toggle-bg: rgba(241, 245, 249, 0.9);
+  --toggle-border: rgba(0, 0, 0, 0.08);
+  --toggle-thumb-from: #fde68a;
+  --toggle-thumb-to: #f59e0b;
+  --toggle-thumb-icon: #78350f;
+}
+
 html, body, #root {
   min-height: 100%;
-  background-color: #030712;
-  background-image: linear-gradient(to bottom right, #030712, #030712, #0f172a);
+  background-color: var(--bg-from);
+  background-image: linear-gradient(to bottom right, var(--bg-from), var(--bg-via), var(--bg-to));
   background-attachment: fixed;
+  transition: background-color 400ms ease, background-image 400ms ease;
 }
 html {
   overscroll-behavior-y: contain;
@@ -26,6 +79,13 @@ html {
   --os-padding-axis: 2px;
 }
 
+/* 라이트 테마에서는 어두운 handle */
+[data-theme="light"] .os-theme-maple.os-theme-dark {
+  --os-handle-bg: #a0a0a0;
+  --os-handle-bg-hover: #707070;
+  --os-handle-bg-active: #505050;
+}
+
 html {
   font-family: "Maplestory", "Noto Sans KR", system-ui, sans-serif;
 }
@@ -62,27 +122,46 @@ input[type="number"] {
   to { opacity: 1; transform: translateY(0); }
 }
 
+/* 테마 전환 뷰 트랜지션 - 부드러운 크로스페이드 */
+::view-transition-old(root),
+::view-transition-new(root) {
+  animation-duration: 400ms;
+  animation-timing-function: ease;
+}
+::view-transition-old(root) {
+  animation-name: themeFadeOut;
+}
+::view-transition-new(root) {
+  animation-name: themeFadeIn;
+}
+@keyframes themeFadeOut {
+  to { opacity: 0; }
+}
+@keyframes themeFadeIn {
+  from { opacity: 0; }
+}
 
-/* 내부 스크롤 영역만 얇은 커스텀 스크롤바 (메인 페이지 스크롤은 기본) */
-*:not(html):not(body) {
+
+/* 커스텀 스크롤바 (테마별) */
+* {
   scrollbar-width: thin;
-  scrollbar-color: rgba(255, 255, 255, 0.1) transparent;
+  scrollbar-color: var(--scrollbar-thumb) var(--scrollbar-track);
 }
-*:not(html):not(body)::-webkit-scrollbar {
-  width: 8px;
-  height: 8px;
+*::-webkit-scrollbar {
+  width: 10px;
+  height: 10px;
 }
-*:not(html):not(body)::-webkit-scrollbar-track {
-  background: transparent;
+*::-webkit-scrollbar-track {
+  background: var(--scrollbar-track);
 }
-*:not(html):not(body)::-webkit-scrollbar-thumb {
-  background: rgba(255, 255, 255, 0.12);
-  border-radius: 4px;
+*::-webkit-scrollbar-thumb {
+  background: var(--scrollbar-thumb);
+  border-radius: 5px;
   transition: background 0.2s;
 }
-*:not(html):not(body)::-webkit-scrollbar-thumb:hover {
-  background: rgba(255, 255, 255, 0.22);
+*::-webkit-scrollbar-thumb:hover {
+  background: var(--scrollbar-thumb-hover);
 }
-*:not(html):not(body)::-webkit-scrollbar-corner {
+*::-webkit-scrollbar-corner {
   background: transparent;
 }
diff --git a/frontend/src/stores/theme.js b/frontend/src/stores/theme.js
new file mode 100644
index 0000000..4f2bade
--- /dev/null
+++ b/frontend/src/stores/theme.js
@@ -0,0 +1,11 @@
+import { create } from 'zustand'
+import { persist } from 'zustand/middleware'
+
+export const useThemeStore = create(persist(
+  (set) => ({
+    theme: 'dark',
+    setTheme: (theme) => set({ theme }),
+    toggleTheme: () => set((s) => ({ theme: s.theme === 'dark' ? 'light' : 'dark' })),
+  }),
+  { name: 'maple-theme' },
+))