diff --git a/electron/main/localFileUrl.ts b/electron/main/localFileUrl.ts
index 1775c9d5..7f9c8e57 100644
--- a/electron/main/localFileUrl.ts
+++ b/electron/main/localFileUrl.ts
@@ -29,6 +29,11 @@ export function filePathFromLocalFileUrl(url: string): string {
   if (parsed.hostname === 'preview' && queryPath) return queryPath;
 
   const pathname = decodeURIComponent(parsed.pathname);
+  // Navigable local HTML uses a fixed host with the absolute filesystem path
+  // in the pathname. Unlike `localfile:///Users/...`, this keeps Chromium from
+  // treating the first path segment as a lower-cased hostname when resolving a
+  // relative link from an injected <base> element.
+  if (parsed.hostname === 'preview') return pathname;
   if (parsed.hostname) return `/${parsed.hostname}${pathname}`;
   return pathname;
 }
diff --git a/src/lib/htmlLocalAssets.ts b/src/lib/htmlLocalAssets.ts
index 29ea3f6b..1bd6c95a 100644
--- a/src/lib/htmlLocalAssets.ts
+++ b/src/lib/htmlLocalAssets.ts
@@ -63,22 +63,32 @@ function encodePathSegments(filePath: string): string {
 
 export function toLocalFileUrl(filePath: string): string {
   if (
-    filePath.startsWith('localfile://') ||
-    filePath.startsWith('file://') ||
     filePath.startsWith('http://') ||
     filePath.startsWith('https://') ||
     filePath.startsWith('blob:') ||
     filePath.startsWith('data:')
   ) {
-    const normalized =
-      filePath.startsWith('file://') && !filePath.startsWith('localfile://')
-        ? filePath.replace(/^file:\/\//, 'localfile://')
-        : filePath;
-    return normalized.endsWith('/') ? normalized : `${normalized}/`;
+    return filePath.endsWith('/') ? filePath : `${filePath}/`;
   }
 
-  const encodedPath = encodePathSegments(filePath);
-  const localFileUrl = `localfile://${encodedPath}`;
+  let localPath = filePath;
+  if (filePath.startsWith('localfile:') || filePath.startsWith('file:')) {
+    const parsed = new URL(filePath);
+    const queryPath = parsed.searchParams.get('path');
+    if (parsed.hostname === 'preview' && queryPath) {
+      localPath = queryPath;
+    } else if (!parsed.hostname || parsed.hostname === 'preview') {
+      localPath = decodeURIComponent(parsed.pathname);
+    } else {
+      localPath = `/${parsed.hostname}${decodeURIComponent(parsed.pathname)}`;
+    }
+  }
+
+  const encodedPath = encodePathSegments(localPath);
+  const rootedPath = encodedPath.startsWith('/')
+    ? encodedPath
+    : `/${encodedPath}`;
+  const localFileUrl = `localfile://preview${rootedPath}`;
   return localFileUrl.endsWith('/') ? localFileUrl : `${localFileUrl}/`;
 }
 
diff --git a/test/unit/electron/localFileUrl.test.ts b/test/unit/electron/localFileUrl.test.ts
index 8171e1ac..f59462b1 100644
--- a/test/unit/electron/localFileUrl.test.ts
+++ b/test/unit/electron/localFileUrl.test.ts
@@ -24,6 +24,17 @@ describe('filePathFromLocalFileUrl', () => {
     ).toBe('/Users/Example User/Report.pdf');
   });
 
+  it('preserves a navigable fixed-host pathname after relative resolution', () => {
+    const linkedUrl = new URL(
+      '../%E7%AC%AC7%E8%AF%BE%E6%97%B6/index.html',
+      'localfile://preview/Users/Example%20User/project/%E7%AC%AC%E4%B8%80%E8%AF%BE%E6%97%B6/'
+    );
+
+    expect(filePathFromLocalFileUrl(linkedUrl.toString())).toBe(
+      '/Users/Example User/project/第7课时/index.html'
+    );
+  });
+
   it('reconstructs legacy macOS URLs whose first segment became a host', () => {
     expect(
       filePathFromLocalFileUrl('localfile://users/4pmtong/report.pdf')
diff --git a/test/unit/lib/htmlLocalAssets.test.ts b/test/unit/lib/htmlLocalAssets.test.ts
index fdc89a1e..77f8d622 100644
--- a/test/unit/lib/htmlLocalAssets.test.ts
+++ b/test/unit/lib/htmlLocalAssets.test.ts
@@ -24,19 +24,27 @@ import {
 describe('toLocalFileUrl', () => {
   it('converts absolute unix paths to localfile base hrefs', () => {
     expect(toLocalFileUrl('/Users/test/canvas_map')).toBe(
-      'localfile:///Users/test/canvas_map/'
+      'localfile://preview/Users/test/canvas_map/'
     );
   });
 
-  it('preserves existing localfile urls and trailing slash', () => {
+  it('upgrades existing localfile urls to the navigable fixed-host format', () => {
     expect(toLocalFileUrl('localfile:///Users/test/canvas_map/')).toBe(
-      'localfile:///Users/test/canvas_map/'
+      'localfile://preview/Users/test/canvas_map/'
     );
   });
 
+  it('converts query-based preview urls to the navigable fixed-host format', () => {
+    expect(
+      toLocalFileUrl(
+        'localfile://preview/?path=%2FUsers%2FExample%20User%2Fcanvas_map'
+      )
+    ).toBe('localfile://preview/Users/Example%20User/canvas_map/');
+  });
+
   it('emits standard localfile urls for Windows drive paths', () => {
     expect(toLocalFileUrl('C:\\Users\\test\\canvas_map')).toBe(
-      'localfile:///C:/Users/test/canvas_map/'
+      'localfile://preview/C:/Users/test/canvas_map/'
     );
   });
 });