diff --git a/interfaces/admin/static/chat.html b/interfaces/admin/static/chat.html
index 6b4d7fb9..b659a668 100644
--- a/interfaces/admin/static/chat.html
+++ b/interfaces/admin/static/chat.html
@@ -9,6 +9,11 @@
     <link rel="stylesheet" href="/admin/assets/theme-deepseek.css" />
     <link rel="stylesheet" href="/admin/assets/theme-presets.css" />
     <style>
+      html,
+      body {
+        width: 100%;
+        min-width: 100%;
+      }
       body.theme-ds-body.chat-standalone-page {
         margin: 0;
         min-height: 100vh;
@@ -24,6 +29,8 @@
         flex-direction: column;
         padding: 0;
         box-sizing: border-box;
+        width: 100%;
+        min-width: 100%;
       }
       .chat-app--login {
         flex: 1;
@@ -37,6 +44,8 @@
       #app .chat-layout {
         flex: 1;
         min-height: 0;
+        width: 100%;
+        min-width: 100%;
       }
       .chat-sess-row {
         display: flex;
diff --git a/interfaces/http/fastapi_app.py b/interfaces/http/fastapi_app.py
index d0f9e12c..fb4f2081 100644
--- a/interfaces/http/fastapi_app.py
+++ b/interfaces/http/fastapi_app.py
@@ -236,6 +236,12 @@ async def _lifespan(app: FastAPI):  # type: ignore[no-untyped-def]
 def create_app() -> FastAPI:
     app = FastAPI(title="ops-gateway", version="0.1", lifespan=_lifespan)
     brand_assets_dir = (Path(PROJECT_ROOT) / "_local" / "branding").resolve()
+    try:
+        brand_assets_dir.mkdir(parents=True, exist_ok=True)
+    except Exception:
+        # Branding assets are optional; if we can't create the directory (permissions),
+        # the static mount should still be safe when empty.
+        pass
     app.mount("/admin/brand-assets", StaticFiles(directory=str(brand_assets_dir), check_dir=False), name="admin-brand-assets")
     app.mount("/admin/assets", StaticFiles(directory=str(admin_static_dir())), name="admin-assets")
     app.include_router(build_admin_router())