One way is to use position:fixed .
<footer style="position:fixed;bottom:0"> Sticky footer? </footer>
Or you can move the footer outside of the paper-header-panel and wrap both of them in a vertically stacked div .
<div class="fit vertical layout"> <paper-header-panel class="flex"> ... </paper-header-panel> <footer> Sticky footer? </footer> </div>
Note that in the root of the div I used fit so that its contents fill the entire page and vertical layout to stack the contents vertically.
See plunker .
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