The front-page issue is solved, you may now have a look of my page. I modified some text in the Tab, now the device with width 720 pixel is displaying fine. But another device with 800 pixels width is not showing the Tab Show. Thx.
http://nathsingc.com/insp/index.php/zh/An additional information to you is, if I hold my mobile device in horizontal, the width is 1280 and the Tab Show is showing correctly. While viewing the front-page and turn the device into vertical, the Tab Show is still showing correctly even the width is now 800. The problem only occur if I load the front-page in vertical (width 800) at the very beginning.