How do I disable position:fixed in web pages?

Question

This website:

http://nautil.us/

has a really annoying header that is always on screen and won't scroll away.

If I right-click on it and 'inspect element' in firefox, then I find that the css contains "position: fixed;", and if I untick this, the header behaves, and scrolls away as God intended headers to do.

Is there some way to get firefox to do this automatically, i.e. remove all position: fixed lines from all pages before rendering them?

edit-------

After a bit of thought, what I want is a bookmarklet that will kill off this sort of thing.

So how to turn SciMonster's promising-looking:

var x = document.querySelectorAll('*'); // get all elements
for (var i = 0; i< x.length; i++) {
    if (x[i].style.position == 'fixed') {
        x[i].style.position = 'static';
    }
}

into

javascript:???

suitable for going in the location field of a firefox bookmark?

With the win condition that if you go to http://nautil.us, and click the bookmarklet button, the floating header stops floating and scrolls away, as if you had deleted position: fixed; in the element inspector.

Answer 1

These two questions on stackoverflow and superuser are very similar.

Arguably, the easiest solution (suggested in the answers on superuser) is to install this greasemonkey script. It has the advantage that it tries to be clever by looping only over relevent html elements and attempting to recognise pseudo-pop-up windows, and not unfixing those. It will automatically run on all loaded webpages unless you edit the @include header line. (I have not actually tested it.)

If you want a bookmarklet, then this should do the job (tested on nautil.us):

javascript:(function(){x=document.querySelectorAll('*');for(i=0;i<x.length;i++){if(getComputedStyle(x[i]).position=="fixed"){x[i].style.position="absolute";}}}())

As a bonus, considering that css position: sticky headers are now also popping up their ugly heads, you can get rid of both them and "fixed" elements:

javascript:(function(){x=document.querySelectorAll('*');for(i=0;i<x.length;i++){elementStyle=getComputedStyle(x[i]);if(elementStyle.position=="fixed"||elementStyle.position=="sticky"){x[i].style.position="absolute";}}}())

Not compressed:

var x = document.querySelectorAll('*');
for(var i=0; i<x.length; i++) {
    elementStyle = getComputedStyle(x[i]);
    if(elementStyle.position=="fixed" || elementStyle.position=="sticky") {
        x[i].style.position="absolute";
    }
}