diff --git a/app/page.tsx b/app/page.tsx
index 254129e..fe8145d 100644
--- a/app/page.tsx
+++ b/app/page.tsx
@@ -617,13 +617,20 @@ export default function TwoFactorAuth() {
       
       const imported = JSON.parse(decrypted)
       if (Array.isArray(imported)) {
-        setTokens([...tokens, ...imported])
+        const existingSecrets = new Set(tokens.map((tk) => tk.secret.toUpperCase()))
+        const newTokens = (imported as TOTPToken[]).filter(
+          (tk) => !existingSecrets.has(tk.secret.toUpperCase())
+        )
+        const skipped = imported.length - newTokens.length
+        setTokens((prev) => [...prev, ...newTokens])
         setImportPassword("")
         setImportFile(null)
         setShowImportPassword(false)
         toast({
           title: t.importSuccess,
-          description: `${t.added} ${imported.length} ${t.importedTokens}`,
+          description: skipped > 0
+            ? `${t.added} ${newTokens.length} ${t.importedTokens}，已跳过 ${skipped} 个重复令牌`
+            : `${t.added} ${newTokens.length} ${t.importedTokens}`,
         })
       }
     } catch {
@@ -1189,14 +1196,14 @@ export default function TwoFactorAuth() {
       <Dialog open={showExportPassword} onOpenChange={setShowExportPassword}>
         <DialogContent>
           <DialogHeader>
-            <DialogTitle>Set Export Password</DialogTitle>
+            <DialogTitle>{t.setExportPassword}</DialogTitle>
           </DialogHeader>
           <div className="space-y-4 py-4">
             <div className="space-y-2">
               <Label>Password</Label>
               <Input
                 type="password"
-                placeholder="Enter a password to protect your backup"
+                placeholder={t.passwordPlaceholder}
                 value={exportPassword}
                 onChange={(e) => setExportPassword(e.target.value)}
               />
@@ -1229,11 +1236,11 @@ export default function TwoFactorAuth() {
       }}>
         <DialogContent>
           <DialogHeader>
-            <DialogTitle>Import Backup</DialogTitle>
+            <DialogTitle>{t.importBackup}</DialogTitle>
           </DialogHeader>
           <div className="space-y-4 py-4">
             <div className="space-y-2">
-              <Label>Select File</Label>
+              <Label>{t.selectFile}</Label>
               <Input
                 type="file"
                 accept=".enc"
@@ -1246,7 +1253,7 @@ export default function TwoFactorAuth() {
               <Label>Password</Label>
               <Input
                 type="password"
-                placeholder="Enter the password for this backup"
+                placeholder={t.passwordInput}
                 value={importPassword}
                 onChange={(e) => setImportPassword(e.target.value)}
               />
diff --git a/components/theme-provider.tsx b/components/theme-provider.tsx
index 20feb83..df0d5bf 100644
--- a/components/theme-provider.tsx
+++ b/components/theme-provider.tsx
@@ -1,12 +1,101 @@
 "use client"
 
-import type * as React from "react"
-import { ThemeProvider as NextThemesProvider } from "next-themes"
+import * as React from "react"
+import { createContext, useContext, useEffect, useState } from "react"
 
-export { useTheme } from "next-themes"
+type Theme = "dark" | "light" | "system"
 
-type ThemeProviderProps = React.ComponentProps<typeof NextThemesProvider>
-
-export function ThemeProvider({ children, ...props }: ThemeProviderProps) {
-  return <NextThemesProvider {...props}>{children}</NextThemesProvider>
+type ThemeProviderProps = {
+  children: React.ReactNode
+  defaultTheme?: Theme
+  storageKey?: string
+  attribute?: string
+  enableSystem?: boolean
+  disableTransitionOnChange?: boolean
+}
+
+type ThemeProviderState = {
+  theme: Theme
+  setTheme: (theme: Theme) => void
+  resolvedTheme?: string
+}
+
+const ThemeProviderContext = createContext<ThemeProviderState | undefined>(undefined)
+
+export function ThemeProvider({
+  children,
+  defaultTheme = "system",
+  storageKey = "theme",
+  ...props
+}: ThemeProviderProps) {
+  const [theme, setTheme] = useState<Theme>(defaultTheme)
+  const [resolvedTheme, setResolvedTheme] = useState<string | undefined>(undefined)
+  const [mounted, setMounted] = useState(false)
+
+  useEffect(() => {
+    setMounted(true)
+    const stored = localStorage.getItem(storageKey) as Theme | null
+    if (stored) {
+      setTheme(stored)
+    }
+  }, [storageKey])
+
+  useEffect(() => {
+    if (!mounted) return
+
+    const root = window.document.documentElement
+
+    root.classList.remove("light", "dark")
+
+    let resolved: string
+    if (theme === "system") {
+      resolved = window.matchMedia("(prefers-color-scheme: dark)").matches ? "dark" : "light"
+    } else {
+      resolved = theme
+    }
+
+    root.classList.add(resolved)
+    setResolvedTheme(resolved)
+  }, [theme, mounted])
+
+  useEffect(() => {
+    if (!mounted || theme !== "system") return
+
+    const mediaQuery = window.matchMedia("(prefers-color-scheme: dark)")
+    const handleChange = () => {
+      const resolved = mediaQuery.matches ? "dark" : "light"
+      const root = window.document.documentElement
+      root.classList.remove("light", "dark")
+      root.classList.add(resolved)
+      setResolvedTheme(resolved)
+    }
+
+    mediaQuery.addEventListener("change", handleChange)
+    return () => mediaQuery.removeEventListener("change", handleChange)
+  }, [theme, mounted])
+
+  const value = {
+    theme,
+    setTheme: (newTheme: Theme) => {
+      localStorage.setItem(storageKey, newTheme)
+      setTheme(newTheme)
+    },
+    resolvedTheme,
+  }
+
+  return (
+    <ThemeProviderContext.Provider value={value}>
+      {children}
+    </ThemeProviderContext.Provider>
+  )
+}
+
+export function useTheme() {
+  const context = useContext(ThemeProviderContext)
+
+  if (context === undefined) {
+    throw new Error("useTheme must be used within a ThemeProvider")
+  }
+
+  return context
 }
diff --git a/lib/i18n.tsx b/lib/i18n.tsx
index f7b4de6..75ad9d8 100644
--- a/lib/i18n.tsx
+++ b/lib/i18n.tsx
@@ -116,6 +116,10 @@ const translations = {
     imageLoadFailed: "图片加载失败",
     duplicateToken: "令牌已存在",
     duplicateTokenDesc: "该密钥的令牌已添加过",
+    setExportPassword: "设置导出密码",
+    passwordPlaceholder: "输入密码以保护您的备份",
+    selectFile: "选择文件",
+    passwordInput: "输入备份密码",
   },
   en: {
     // Header
@@ -227,6 +231,10 @@ const translations = {
     imageLoadFailed: "Failed to load image",
     duplicateToken: "Token already exists",
     duplicateTokenDesc: "A token with this secret key has already been added",
+    setExportPassword: "Set Export Password",
+    passwordPlaceholder: "Enter a password to protect your backup",
+    selectFile: "Select File",
+    passwordInput: "Enter backup password",
   },
 }