"For elements whose layout is governed by the CSS box model, any value other than none for the transform results in the creation of both a stacking context and a containing block. The object acts as a containing block for fixed positioned descendants."
<div style="transform: translate3d(0,0,0);overflow:hidden">
<img style="position:fixed; ..." />
To position the element relative to a parent element simply set a transform style to the parent.
The parent will now act as a containing block for fixed children.