XF 1.2 home page shifts downward about 1/4 inch, when navigating from elsewhere

It is kind of weird, but every time I click my home tab (the first tab) from other tabs, the web page would shift down about 1/4 inch. Other tabs do not seem to have this issue.

This is my website. http://www.obd-chinese.com/

I wonder if anyone had similar issues before? Thanks.
Thank you very much.

I have opened pagenode_container, but could not find the codes of <body class="node12" data-twttr-rendered="true" style>, as highlighted in your earlier reply.