Fixed position breaks on header when I click on the \"Search Form\" text box field. It simply detaches from the top of the page (as it\'s fixed up there) and starts floating
Based on this good analysis of this issue, I've used this in html and body elements in css:
html,body{ -webkit-overflow-scrolling : touch !important; overflow: auto !important; height: 100% !important; }
it's working great for me.