diff --git a/packages/i18n/src/dev.ts b/packages/i18n/src/dev.ts
index 885fa66..6ebfcbb 100644
--- a/packages/i18n/src/dev.ts
+++ b/packages/i18n/src/dev.ts
@@ -1,10 +1,16 @@
 import { DEFAULT_LOCALE, isLocale, type Locale } from './lib/locale.js';
 
-import type { RsbuildConfig } from '@rsbuild/core';
+import type { RsbuildConfig, RsbuildPlugin } from '@rsbuild/core';
 
 /**
  * Returns a partial Rsbuild config that enables locale-aware builds.
  *
+ * The locale MDX replacement is provided as an Rsbuild plugin (rather than a
+ * `tools.rspack` function) so that `mergeConfig` can safely concatenate it
+ * with the service's own `plugins` array. A `tools.rspack` function would be
+ * silently dropped by `mergeConfig` when the service config also defines
+ * `tools.rspack` as a plain object.
+ *
  * Designed to be merged with defineServiceConfig() in each service's rsbuild.config.ts:
  *
  * @example
@@ -19,6 +25,30 @@ export function localeRsbuildConfig(): RsbuildConfig {
   const rawLocale = process.env.LOCALE ?? '';
   const locale: Locale = isLocale(rawLocale) ? rawLocale : DEFAULT_LOCALE;
 
+  const localePlugins: RsbuildPlugin[] = [];
+
+  if (locale !== DEFAULT_LOCALE) {
+    localePlugins.push({
+      name: 'ermnvldmr:locale-mdx-replacement',
+      setup(api) {
+        // Resolve .en.mdx imports to the locale-specific file when LOCALE != 'en'.
+        // The canonical import is always `.en.mdx`; other locales are resolved here.
+        api.modifyRspackConfig((config, { rspack }) => {
+          config.plugins = [
+            ...(config.plugins ?? []),
+            new rspack.NormalModuleReplacementPlugin(
+              /\.en\.mdx$/,
+              (resource: { request: string }) => {
+                resource.request = resource.request.replace(/\.en\.mdx$/, `.${locale}.mdx`);
+              }
+            ),
+          ];
+          return config;
+        });
+      },
+    });
+  }
+
   return {
     source: {
       define: {
@@ -36,24 +66,7 @@ export function localeRsbuildConfig(): RsbuildConfig {
       },
       assetPrefix: `/${locale}/`,
     },
-    tools: {
-      rspack: (config, { rspack }) => {
-        // Resolve .en.mdx imports to the locale-specific file when LOCALE != 'en'.
-        // The canonical import is always `.en.mdx`; other locales are resolved here.
-        if (locale !== DEFAULT_LOCALE) {
-          config.plugins = [
-            ...config.plugins,
-            new rspack.NormalModuleReplacementPlugin(
-              /\.en\.mdx$/,
-              (resource: { request: string }) => {
-                resource.request = resource.request.replace(/\.en\.mdx$/, `.${locale}.mdx`);
-              }
-            ),
-          ];
-        }
-        return config;
-      },
-    },
+    plugins: localePlugins,
   };
 }
 
diff --git a/packages/rsbuild-config/src/lib/config/ssg.ts b/packages/rsbuild-config/src/lib/config/ssg.ts
index e483bd5..97588fd 100644
--- a/packages/rsbuild-config/src/lib/config/ssg.ts
+++ b/packages/rsbuild-config/src/lib/config/ssg.ts
@@ -111,6 +111,7 @@ export function ssgPlugin(): RsbuildPlugin {
           preload?: string;
           inlineFonts?: boolean;
           pruneSource?: boolean;
+          reduceInlineStyles?: boolean;
         }) => { process(html: string): Promise<string> };
 
         // critters `path` is the filesystem root that corresponds to publicPath.
@@ -121,9 +122,10 @@ export function ssgPlugin(): RsbuildPlugin {
         const critters = new Critters({
           path: webDistPath,
           publicPath: configuredAssetPrefix,
-          preload: 'swap',     // <link rel="preload" as="style" onload="this.rel='stylesheet'">
-          inlineFonts: false,  // fonts are handled via separate <link rel="preload"> tags
-          pruneSource: false,  // keep full CSS file for post-hydration correctness
+          preload: 'swap',              // <link rel="preload" as="style" onload="this.rel='stylesheet'">
+          inlineFonts: false,           // fonts are handled via separate <link rel="preload"> tags
+          pruneSource: false,           // keep full CSS file for post-hydration correctness
+          reduceInlineStyles: false,    // preserve theme init styles (prevents .dark rule from being stripped)
         });
 
         for (const entryName of entryNames) {
diff --git a/services/www/rsbuild.config.ts b/services/www/rsbuild.config.ts
index 74b67a8..b8efb4a 100644
--- a/services/www/rsbuild.config.ts
+++ b/services/www/rsbuild.config.ts
@@ -6,7 +6,8 @@ import { pluginMdx } from '@rsbuild/plugin-mdx';
 import remarkFrontmatter from 'remark-frontmatter';
 import remarkMdxFrontmatter from 'remark-mdx-frontmatter';
 
-const fontBase = 'static/font';
+const locale = process.env.LOCALE ?? 'en';
+const fontBase = `/${locale}/static/font`;
 
 export default defineServiceConfig(
   mergeConfig(localeRsbuildConfig(), {
@@ -44,6 +45,7 @@ export default defineServiceConfig(
             href: `${fontBase}/lato-400.woff2`,
             crossorigin: true,
           },
+          publicPath: false,
         },
         {
           tag: 'link',
@@ -54,6 +56,7 @@ export default defineServiceConfig(
             href: `${fontBase}/lato-700.woff2`,
             crossorigin: true,
           },
+          publicPath: false,
         },
         {
           tag: 'link',
@@ -64,6 +67,7 @@ export default defineServiceConfig(
             href: `${fontBase}/eb-garamond-var.woff2`,
             crossorigin: true,
           },
+          publicPath: false,
         },
       ],
     },