add and use webp bgBoxMainBottom version with alpha chanel

diff --git a/style/2010/grey/screen.css b/style/2010/grey/screen.css
index 0d657b5baa8a68e8ac329942f8e657a6fd9a936a..ddae91e952a6cf297c1a373d36c9a778e3709fa3 100644 (file)
--- a/style/2010/grey/screen.css
+++ b/style/2010/grey/screen.css
@@ -404,7 +404,7 @@ body * {
        height: 16px;
        left: 0;
        bottom: 0;
-       background-image: url(bgBoxMainBottom.gif);
+       background-image: url(bgBoxMainBottom.webp);
        background-position: 0 100%;
        background-repeat: no-repeat;
 }