Well, I found a way to work.
<body style="overflow:hidden;">
<header style="width:auto;display:block;padding:12px;text-align:center;background-color:#1276c7;color:white;position:fixed;top:0;left:0;right:0;opacity:1;">FIXED HEADER</header>
<div role="main" style="height:100%;overflow-y:scroll;padding:60px 0;box-sizing:border-box;-webkit-overflow-scrolling: touch;">
<article>
...(content)...
</article>
</div>
</body>
It appears that we need an inner scrollable element and remove overflow on body. I overthought it, it seems. Hope this helps someone.