Merge pull request #915 from uzegonemad/hotfix/scroll-up-zindex

Fix z-index on scroll to top button

src/UI/Content/theme.less

@@ -81,6 +81,7 @@
 
   .opacity   (0.2);
   position  : fixed;
+  z-index   : 9999;
   bottom    : 50px;
   right     : 50px;
   display   : none;