diff --git a/web/frontend/package.json b/web/frontend/package.json
index a8a963ca9..7595c46bf 100644
--- a/web/frontend/package.json
+++ b/web/frontend/package.json
@@ -26,6 +26,7 @@
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
     "dayjs": "^1.11.20",
+    "highlight.js": "^11.11.1",
     "i18next": "^26.0.3",
     "i18next-browser-languagedetector": "^8.2.1",
     "jotai": "^2.19.1",
diff --git a/web/frontend/pnpm-lock.yaml b/web/frontend/pnpm-lock.yaml
index e12e6b351..721bd7e75 100644
--- a/web/frontend/pnpm-lock.yaml
+++ b/web/frontend/pnpm-lock.yaml
@@ -35,6 +35,9 @@ importers:
       dayjs:
         specifier: ^1.11.20
         version: 1.11.20
+      highlight.js:
+        specifier: ^11.11.1
+        version: 11.11.1
       i18next:
         specifier: ^26.0.3
         version: 26.0.3(typescript@5.9.3)
diff --git a/web/frontend/src/components/agent/skills/detail-sheet.tsx b/web/frontend/src/components/agent/skills/detail-sheet.tsx
index 41f56b057..4579926d8 100644
--- a/web/frontend/src/components/agent/skills/detail-sheet.tsx
+++ b/web/frontend/src/components/agent/skills/detail-sheet.tsx
@@ -172,7 +172,7 @@ export function DetailSheet({
               </div>
 
               {detailView === "preview" ? (
-                <div className="prose prose-zinc dark:prose-invert prose-sm sm:prose-base prose-pre:rounded-xl prose-pre:border prose-pre:border-border/40 prose-pre:bg-zinc-950/90 prose-pre:shadow-sm prose-headings:tracking-tight prose-a:text-primary prose-a:no-underline hover:prose-a:underline max-w-none">
+                <div className="prose prose-zinc dark:prose-invert prose-sm sm:prose-base prose-pre:rounded-xl prose-pre:border prose-pre:border-border/40 prose-pre:bg-zinc-100 prose-pre:p-0 prose-pre:shadow-sm dark:prose-pre:bg-zinc-950/90 prose-headings:tracking-tight prose-a:text-primary prose-a:no-underline hover:prose-a:underline max-w-none">
                   <ReactMarkdown
                     remarkPlugins={[remarkGfm]}
                     rehypePlugins={[rehypeRaw, rehypeSanitize, rehypeHighlight]}
diff --git a/web/frontend/src/components/chat/assistant-message.tsx b/web/frontend/src/components/chat/assistant-message.tsx
index 9732a6b0f..55b7b9bf6 100644
--- a/web/frontend/src/components/chat/assistant-message.tsx
+++ b/web/frontend/src/components/chat/assistant-message.tsx
@@ -64,7 +64,7 @@ export function AssistantMessage({
       >
         <div
           className={cn(
-            "prose dark:prose-invert prose-pre:my-2 prose-pre:overflow-x-auto prose-pre:rounded-lg prose-pre:border prose-pre:bg-zinc-950 prose-pre:p-3 max-w-none [overflow-wrap:anywhere] break-words",
+            "prose dark:prose-invert prose-pre:my-2 prose-pre:overflow-x-auto prose-pre:rounded-lg prose-pre:border prose-pre:bg-zinc-100 prose-pre:p-0 dark:prose-pre:bg-zinc-950 max-w-none [overflow-wrap:anywhere] break-words",
             isThought
               ? "prose-p:my-1.5 p-3 text-[13px] leading-relaxed opacity-90"
               : "prose-p:my-2 p-4 text-[15px] leading-relaxed",
diff --git a/web/frontend/src/hooks/use-highlight-theme.ts b/web/frontend/src/hooks/use-highlight-theme.ts
new file mode 100644
index 000000000..47b782679
--- /dev/null
+++ b/web/frontend/src/hooks/use-highlight-theme.ts
@@ -0,0 +1,45 @@
+import { useEffect } from "react"
+
+import githubDarkCss from "highlight.js/styles/github-dark.css?inline"
+import githubLightCss from "highlight.js/styles/github.css?inline"
+
+const THEME_STYLE_ID = "hljs-theme-style"
+
+function getOrCreateThemeStyleElement() {
+  let styleElement = document.getElementById(THEME_STYLE_ID)
+  if (!styleElement) {
+    styleElement = document.createElement("style")
+    styleElement.id = THEME_STYLE_ID
+    document.head.appendChild(styleElement)
+  }
+  return styleElement
+}
+
+export function useHighlightTheme() {
+  useEffect(() => {
+    const root = document.documentElement
+    const styleElement = getOrCreateThemeStyleElement()
+
+    const applyTheme = () => {
+      const nextThemeCss = root.classList.contains("dark")
+        ? githubDarkCss
+        : githubLightCss
+      styleElement.textContent = nextThemeCss
+    }
+
+    applyTheme()
+
+    const observer = new MutationObserver(() => {
+      applyTheme()
+    })
+
+    observer.observe(root, {
+      attributes: true,
+      attributeFilter: ["class"],
+    })
+
+    return () => {
+      observer.disconnect()
+    }
+  }, [])
+}
diff --git a/web/frontend/src/index.css b/web/frontend/src/index.css
index 7958233f3..fc55a3a32 100644
--- a/web/frontend/src/index.css
+++ b/web/frontend/src/index.css
@@ -157,69 +157,6 @@
   height: calc(100svh - 3.5rem);
 }
 
-/* Markdown code highlighting (rehype-highlight / highlight.js classes) */
-.prose pre code.hljs,
-.prose pre code[class*="language-"] {
-  display: block;
-  overflow-x: auto;
-  background: transparent;
-  padding: 0;
-  color: #e4e4e7;
-}
-
-.prose pre code .hljs-comment,
-.prose pre code .hljs-quote {
-  color: #71717a;
-}
-
-.prose pre code .hljs-keyword,
-.prose pre code .hljs-selector-tag,
-.prose pre code .hljs-subst {
-  color: #f472b6;
-}
-
-.prose pre code .hljs-string,
-.prose pre code .hljs-doctag,
-.prose pre code .hljs-regexp,
-.prose pre code .hljs-addition,
-.prose pre code .hljs-attribute,
-.prose pre code .hljs-template-tag,
-.prose pre code .hljs-template-variable {
-  color: #34d399;
-}
-
-.prose pre code .hljs-number,
-.prose pre code .hljs-literal,
-.prose pre code .hljs-bullet,
-.prose pre code .hljs-meta,
-.prose pre code .hljs-built_in,
-.prose pre code .hljs-builtin-name,
-.prose pre code .hljs-symbol,
-.prose pre code .hljs-variable,
-.prose pre code .hljs-link,
-.prose pre code .hljs-type,
-.prose pre code .hljs-selector-class,
-.prose pre code .hljs-selector-attr,
-.prose pre code .hljs-selector-pseudo {
-  color: #22d3ee;
-}
-
-.prose pre code .hljs-title,
-.prose pre code .hljs-section,
-.prose pre code .hljs-name,
-.prose pre code .hljs-selector-id,
-.prose pre code .hljs-deletion {
-  color: #60a5fa;
-}
-
-.prose pre code .hljs-emphasis {
-  font-style: italic;
-}
-
-.prose pre code .hljs-strong {
-  font-weight: 700;
-}
-
 /* Typing indicator animations */
 @keyframes shimmer {
   0% {
diff --git a/web/frontend/src/main.tsx b/web/frontend/src/main.tsx
index 81e72c29f..17eb18291 100644
--- a/web/frontend/src/main.tsx
+++ b/web/frontend/src/main.tsx
@@ -3,6 +3,7 @@ import { RouterProvider, createRouter } from "@tanstack/react-router"
 import { StrictMode } from "react"
 import ReactDOM from "react-dom/client"
 
+import { useHighlightTheme } from "./hooks/use-highlight-theme"
 import "./i18n"
 import "./index.css"
 import { routeTree } from "./routeTree.gen"
@@ -22,14 +23,22 @@ declare module "@tanstack/react-router" {
   }
 }
 
+function AppProviders() {
+  useHighlightTheme()
+
+  return (
+    <QueryClientProvider client={queryClient}>
+      <RouterProvider router={router} />
+    </QueryClientProvider>
+  )
+}
+
 const rootElement = document.getElementById("root")!
 if (!rootElement.innerHTML) {
   const root = ReactDOM.createRoot(rootElement)
   root.render(
     <StrictMode>
-      <QueryClientProvider client={queryClient}>
-        <RouterProvider router={router} />
-      </QueryClientProvider>
+      <AppProviders />
     </StrictMode>,
   )
 }