html - Why not used position:fixed for a "sticky" footer?

Question

I've seen Ryan Fait's method for sticky footer as well as one here and here.

Why are these people making templates for sticky footers when #footer{position:fixed; bottom:0;} will suffice?

EDIT:

I will add that using position: fixed; for a footer does break margin: auto; centering in (at least) some browsers, thus creating the need for a wrapper tag. Part of my problem with the above mentioned methods is the extra tags which are confusing, syntactically incorrect (for the "HTML purists") and it eats bandwidth. However, a single wrapper around the footer is still, in my opinion, better than a whole jumbled page template to have to start with. And, "my" way is still more straightforward and eats less bandwidth.

Answer 1

The difference between using position: fixed and Ryan Fait's method¹ is pretty fundamental.

When using position: fixed, the footer is always visible, and that's not what a sticky footer is trying to do.
The meaning of a sticky footer is to stay sticked to the bottom, except if the content is longer than the viewport height. In that case, the sticky footer will act like a normal footer, appearing just below the page content.

Here you can see the effect of a sticky footer. In the Result window, you see that the footer stays at the bottom of the page. Click on the 'Add content' button to add content, and then you will see that the footer shifts down to stay below the content.

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^{1. This is a snapshot of 10 January 2013 from the Wayback Machine, as Ryan's website itself does not contain the original post any longer.}