I find that when I position an element fixed, it doesn’t matter if the parent is positioned relative or not, it will position fixed, relative to the window?
#wrapper {
width: 300px;
background: orange;
margin: 0 auto;
position: relative;
}
#feedback {
position: fixed;
right: 0;
top: 120px;
}<div id="wrapper">
...
<a id="feedback" href="#">Feedback</a>
</div>