When the width is narrow(about less than 768px), the vector skin changes its form in order to fit in narrow width (such as moving sidebar down). However, I found a serious problem. The dropdown of right tab is concealed by right advertisements, like below screenshot.
(Actually I slightly modified css settings of dropdown menu by extending it to left side, but if I didn't modify the css, the dropdown menu would be concealed by right ads, because it is under the right ads.)
Since I found it causes a serious inconvenience of using wiki, I request to fix the problem.