diff --git a/scripts/package-extension.js b/scripts/package-extension.js
index 37b6d44..f193c00 100644
--- a/scripts/package-extension.js
+++ b/scripts/package-extension.js
@@ -192,6 +192,17 @@ async function packageExtension({
   for (const relativePath of archiveFiles) {
     let contents = await readFile(path.join(rootDirectory, relativePath));
 
+    if (target === "chromium" && relativePath === "content.css") {
+      contents = Buffer.from(
+        contents
+          .toString("utf8")
+          .replaceAll(
+            'url("fonts/',
+            'url("chrome-extension://__MSG_@@extension_id__/fonts/'
+          )
+      );
+    }
+
     if (relativePath === "manifest.json") {
       const manifest = createManifest(contents, version, target);
       contents = Buffer.from(`${JSON.stringify(manifest, null, 2)}\n`);
diff --git a/tests/package-extension.test.js b/tests/package-extension.test.js
index 3d1798d..f1c37ac 100644
--- a/tests/package-extension.test.js
+++ b/tests/package-extension.test.js
@@ -74,6 +74,10 @@ test("builds a deterministic unsigned XPI with the release version and runtime f
 
   assert.equal(first.archiveName, "glagolify-9.8.7.xpi");
   assert.deepEqual([...entries.keys()], [...FIREFOX_ARCHIVE_FILES]);
+  assert.deepEqual(
+    entries.get("content.css"),
+    await readFile(path.join(rootDirectory, "content.css"))
+  );
   const manifest = JSON.parse(entries.get("manifest.json"));
   assert.equal(manifest.version, "9.8.7");
   assert.equal(manifest.manifest_version, 2);
@@ -127,6 +131,22 @@ test("builds a Chromium MV3 ZIP with Chromium manifest fields and raster icons",
   ]);
   assert.equal(manifest.icons["128"], "icons/icon-128.png");
 
+  const contentCss = entries.get("content.css").toString("utf8");
+  const fontUrls = [...contentCss.matchAll(/src: url\("([^"]+)"\)/g)].map(
+    (match) => match[1]
+  );
+  const extensionUrl = "chrome-extension://__MSG_@@extension_id__/";
+  assert.equal(fontUrls.length, 4);
+  for (const fontUrl of fontUrls) {
+    assert.equal(fontUrl.startsWith(extensionUrl), true);
+    const relativePath = fontUrl.slice(extensionUrl.length);
+    assert.equal(entries.has(relativePath), true);
+    assert.equal(
+      manifest.web_accessible_resources[0].resources.includes(relativePath),
+      true
+    );
+  }
+
   for (const relativePath of CHROMIUM_ARCHIVE_FILES.filter((name) =>
     name.endsWith(".png")
   )) {