diff --git a/services/api-server/src/api_server/html5_responses.py b/services/api-server/src/api_server/html5_responses.py
index 019929c..e0ebf18 100644
--- a/services/api-server/src/api_server/html5_responses.py
+++ b/services/api-server/src/api_server/html5_responses.py
@@ -20,7 +20,7 @@ HTML5_CONTENT_SECURITY_POLICY = (
 class Html5StaticFiles(StaticFiles):
     def file_response(self, *args, **kwargs):
         response = super().file_response(*args, **kwargs)
-        response.headers.setdefault("Cache-Control", "public, max-age=86400")
+        response.headers.setdefault("Cache-Control", "public, max-age=31536000, immutable")
         response.headers.setdefault("X-Content-Type-Options", "nosniff")
         return response
 
diff --git a/services/api-server/tests/test_api.py b/services/api-server/tests/test_api.py
index e3ecf6a..85fedd4 100644
--- a/services/api-server/tests/test_api.py
+++ b/services/api-server/tests/test_api.py
@@ -396,20 +396,26 @@ def test_html5_server_rendered_project_editor(tmp_path: Path):
     htmx_asset = client.get("/html5/assets/htmx.min.js")
     assert htmx_asset.status_code == 200
     assert "javascript" in htmx_asset.headers["content-type"]
-    assert htmx_asset.headers["cache-control"] == "public, max-age=86400"
+    assert htmx_asset.headers["cache-control"] == "public, max-age=31536000, immutable"
     assert htmx_asset.headers["x-content-type-options"] == "nosniff"
     assert "htmx" in htmx_asset.text
     sse_asset = client.get("/html5/assets/htmx-ext-sse.js")
     assert sse_asset.status_code == 200
     assert "javascript" in sse_asset.headers["content-type"]
-    assert sse_asset.headers["cache-control"] == "public, max-age=86400"
+    assert sse_asset.headers["cache-control"] == "public, max-age=31536000, immutable"
     assert sse_asset.headers["x-content-type-options"] == "nosniff"
     assert "sse" in sse_asset.text
     css_asset = client.get("/html5/assets/html5.css")
     assert css_asset.status_code == 200
     assert "text/css" in css_asset.headers["content-type"]
-    assert css_asset.headers["cache-control"] == "public, max-age=86400"
+    assert css_asset.headers["cache-control"] == "public, max-age=31536000, immutable"
     assert css_asset.headers["x-content-type-options"] == "nosniff"
+    assert css_asset.headers["etag"]
+    cached_css_asset = client.get("/html5/assets/html5.css", headers={"If-None-Match": css_asset.headers["etag"]})
+    assert cached_css_asset.status_code == 304
+    assert cached_css_asset.headers["cache-control"] == "public, max-age=31536000, immutable"
+    assert cached_css_asset.headers["x-content-type-options"] == "nosniff"
+    assert cached_css_asset.content == b""
     assert ".workspace" in css_asset.text