Fix: add /cover.png endpoint for static file serving

app.py

@@ -134,6 +134,15 @@ async def serve_frontend():
     return FileResponse(FRONTEND_PATH)
 
 
+@app.get("/cover.png")
+async def serve_cover():
+    """提供背景图片 cover.png"""
+    cover_path = os.path.join(BASE_DIR, 'cover.png')
+    if os.path.exists(cover_path):
+        return FileResponse(cover_path, media_type='image/png')
+    raise HTTPException(status_code=404, detail="cover not found")
+
+
 @app.post("/api/login")
 async def login(username: str = Form(...)):
     try:

index.html

@@ -32,7 +32,7 @@ body{
 /* === 背景图 cover.png === */
 .bg-cover{
   position:fixed;inset:0;z-index:-3;
-  background-image:url('cover.png');
+  background-image:url('/cover.png');
   background-size:cover;background-position:center;
   opacity:0.35;
 }
@@ -78,7 +78,7 @@ body{
 }
 .parallax-bg .bg-cover-inner{
   position:absolute;inset:0;
-  background-image:url('cover.png');
+  background-image:url('/cover.png');
   background-size:cover;background-position:center;
   opacity:0.3;
 }