diff --git a/frontend-web/index.html b/frontend-web/index.html
index e1d8ce8a..f6fe9779 100644
--- a/frontend-web/index.html
+++ b/frontend-web/index.html
@@ -1,7 +1,18 @@
 <!doctype html>
-<html lang="en-US">
+<html lang="en-US" suppressHydrationWarning>
   <head>
     <meta charset="UTF-8" />
+    <script>
+      (function () {
+        try {
+          var t = localStorage.getItem("strategy-theme");
+          var root = document.documentElement;
+          root.classList.remove("dark", "light");
+          if (t === "light") return;
+          root.classList.add("dark");
+        } catch (e) {}
+      })();
+    </script>
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>CM 助手</title>
   </head>
diff --git a/frontend-web/src/App.tsx b/frontend-web/src/App.tsx
index 23f7257b..1f7554d8 100644
--- a/frontend-web/src/App.tsx
+++ b/frontend-web/src/App.tsx
@@ -25,7 +25,9 @@ function AppProviders({ children }: { children: React.ReactNode }) {
   return (
     <NextThemesProvider
       attribute="class"
-      enableSystem
+      storageKey="strategy-theme"
+      defaultTheme="dark"
+      enableSystem={false}
       disableTransitionOnChange
       forcedTheme={forcedTheme}
     >
diff --git a/frontend-web/src/components/workspace/settings/appearance-settings-page.tsx b/frontend-web/src/components/workspace/settings/appearance-settings-page.tsx
index cd1feb3b..95195df3 100644
--- a/frontend-web/src/components/workspace/settings/appearance-settings-page.tsx
+++ b/frontend-web/src/components/workspace/settings/appearance-settings-page.tsx
@@ -1,9 +1,10 @@
 "use client";
 
-import { MonitorSmartphoneIcon, MoonIcon, SunIcon } from "lucide-react";
-import { useTheme } from "next-themes";
+import { MoonIcon, SunIcon } from "lucide-react";
 import { useMemo, type ComponentType, type SVGProps } from "react";
 
+import { useTheme } from "@/contexts/ThemeContext";
+
 import {
   Select,
   SelectContent,
@@ -27,18 +28,12 @@ const languageOptions: { value: Locale; label: string }[] = [
 
 export function AppearanceSettingsPage() {
   const { t, locale, changeLocale } = useI18n();
-  const { theme, setTheme, systemTheme } = useTheme();
-  const currentTheme = (theme ?? "system") as "system" | "light" | "dark";
+  const { theme, setTheme } = useTheme();
+  const currentTheme = theme;
   const [settings, setSettings] = useLocalSettings();
 
   const themeOptions = useMemo(
     () => [
-      {
-        id: "system",
-        label: t.settings.appearance.system,
-        description: t.settings.appearance.systemDescription,
-        icon: MonitorSmartphoneIcon,
-      },
       {
         id: "light",
         label: t.settings.appearance.light,
@@ -57,8 +52,6 @@ export function AppearanceSettingsPage() {
       t.settings.appearance.darkDescription,
       t.settings.appearance.light,
       t.settings.appearance.lightDescription,
-      t.settings.appearance.system,
-      t.settings.appearance.systemDescription,
     ],
   );
 
@@ -68,7 +61,7 @@ export function AppearanceSettingsPage() {
         title={t.settings.appearance.themeTitle}
         description={t.settings.appearance.themeDescription}
       >
-        <div className="grid gap-3 lg:grid-cols-3">
+        <div className="grid gap-3 lg:grid-cols-2">
           {themeOptions.map((option) => (
             <ThemePreviewCard
               key={option.id}
@@ -76,8 +69,7 @@ export function AppearanceSettingsPage() {
               label={option.label}
               description={option.description}
               active={currentTheme === option.id}
-              mode={option.id as "system" | "light" | "dark"}
-              systemTheme={systemTheme}
+              mode={option.id as "light" | "dark"}
               onSelect={(value) => setTheme(value)}
             />
           ))}
@@ -144,19 +136,16 @@ function ThemePreviewCard({
   description,
   active,
   mode,
-  systemTheme,
   onSelect,
 }: {
   icon: ComponentType<SVGProps<SVGSVGElement>>;
   label: string;
   description: string;
   active: boolean;
-  mode: "system" | "light" | "dark";
-  systemTheme?: string;
-  onSelect: (mode: "system" | "light" | "dark") => void;
+  mode: "light" | "dark";
+  onSelect: (mode: "light" | "dark") => void;
 }) {
-  const previewMode =
-    mode === "system" ? (systemTheme === "dark" ? "dark" : "light") : mode;
+  const previewMode = mode;
   return (
     <button
       type="button"
diff --git a/frontend-web/src/contexts/ThemeContext.tsx b/frontend-web/src/contexts/ThemeContext.tsx
index 4ea9a21b..55cda911 100644
--- a/frontend-web/src/contexts/ThemeContext.tsx
+++ b/frontend-web/src/contexts/ThemeContext.tsx
@@ -1,4 +1,10 @@
-import React, { createContext, useContext, useState, useEffect, ReactNode } from 'react';
+import React, {
+  createContext,
+  useContext,
+  useEffect,
+  useState,
+  type ReactNode,
+} from 'react';
 import { useTheme as useNextTheme } from 'next-themes';
 
 // 主题类型
@@ -76,12 +82,24 @@ const themes: Record<ThemeType, ThemeConfig> = {
   },
 };
 
+const STORAGE_KEY = 'strategy-theme';
+
+function readPersistedTheme(): ThemeType {
+  if (typeof window === 'undefined') {
+    return 'dark';
+  }
+  const saved = localStorage.getItem(STORAGE_KEY);
+  return saved === 'light' ? 'light' : 'dark';
+}
+
 // 主题上下文
 interface ThemeContextType {
   theme: ThemeType;
   themeConfig: ThemeConfig;
   toggleTheme: () => void;
   setTheme: (theme: ThemeType) => void;
+  /** next-themes 完成挂载前为 false，避免 hydration 与 DOM 不同步 */
+  mounted: boolean;
 }
 
 const ThemeContext = createContext<ThemeContextType | undefined>(undefined);
@@ -92,35 +110,52 @@ interface ThemeProviderProps {
 }
 
 export const ThemeProvider: React.FC<ThemeProviderProps> = ({ children }) => {
-  const { setTheme: setNextTheme } = useNextTheme();
-  const [theme, setThemeState] = useState<ThemeType>(() => {
-    // 从 localStorage 读取保存的主题
-    const saved = localStorage.getItem('strategy-theme');
-    return (saved as ThemeType) || 'dark';
-  });
+  const { resolvedTheme, setTheme: setNextTheme } = useNextTheme();
+  const [mounted, setMounted] = useState(false);
 
-  // 切换主题
-  const toggleTheme = () => {
-    setThemeState((prev) => (prev === 'dark' ? 'light' : 'dark'));
-  };
-
-  // 设置特定主题
-  const setTheme = (newTheme: ThemeType) => {
-    setThemeState(newTheme);
-  };
-
-  // 保存到 localStorage，并同步 html class 与 next-themes
   useEffect(() => {
-    localStorage.setItem('strategy-theme', theme);
-    document.documentElement.classList.remove('dark', 'light');
-    document.documentElement.classList.add(theme);
-    setNextTheme(theme);
-  }, [theme, setNextTheme]);
+    setMounted(true);
+  }, []);
+
+  // 迁移 / 规范化 localStorage，避免与 next-themes 冲突导致闪回浅色
+  useEffect(() => {
+    if (!mounted) return;
+    const current = localStorage.getItem(STORAGE_KEY);
+    const legacy = localStorage.getItem('theme');
+
+    if (current !== 'light' && current !== 'dark') {
+      const fallback =
+        legacy === 'light' || legacy === 'dark' ? legacy : 'dark';
+      setNextTheme(fallback);
+    } else if (!current && legacy && (legacy === 'light' || legacy === 'dark')) {
+      setNextTheme(legacy);
+    }
+
+    if (legacy) {
+      localStorage.removeItem('theme');
+    }
+  }, [mounted, setNextTheme]);
+
+  const theme: ThemeType = mounted
+    ? resolvedTheme === 'light'
+      ? 'light'
+      : 'dark'
+    : readPersistedTheme();
+
+  const toggleTheme = () => {
+    setNextTheme(theme === 'dark' ? 'light' : 'dark');
+  };
+
+  const setTheme = (newTheme: ThemeType) => {
+    setNextTheme(newTheme);
+  };
 
   const themeConfig = themes[theme];
 
   return (
-    <ThemeContext.Provider value={{ theme, themeConfig, toggleTheme, setTheme }}>
+    <ThemeContext.Provider
+      value={{ theme, themeConfig, toggleTheme, setTheme, mounted }}
+    >
       {children}
     </ThemeContext.Provider>
   );