change bg move speed

src/scss/pages/_rumble.scss

@@ -42,7 +42,7 @@
       background-size: 45px 45px, 45px 45px, 9px 9px, 9px 9px;
       background-position: -1.8px -1.8px, -1.8px -1.8px, -0.9px -0.9px, -0.9px -0.9px;
 
-      animation: moveBg 30s ease-in-out infinite;
+      animation: moveBg 20s ease-in-out infinite;
     }
     img {
       width: 60vh;