feat: improve visual consistency in item background

Adjusted the repeating-conic-gradient to enhance visual consistency by using a transparent color stop, addressing a subtle visual artifact.

src/assets/item.css

@@ -146,7 +146,7 @@
       background: #ccc 60% 60% / 3000px 3000px;
       background-image: repeating-conic-gradient(
         #999 0 0.0001%,
-        #000 0 0.0002%
+        #0000 0 0.0002%
       );
     }