+/* override minimal-xul.css */
+scrollbarbutton[sbattr="scrollbar-up-top"],
+scrollbarbutton[sbattr="scrollbar-down-bottom"],
+scrollbarbutton[sbattr="scrollbar-up-top"]:not(:-moz-system-metric(scrollbar-start-backward)),
+scrollbarbutton[sbattr="scrollbar-down-bottom"]:not(:-moz-system-metric(scrollbar-end-forward)) {
+ display: -moz-box;
+}