Blank space created when URL bar is pushed off screen(mobile)

[bkr32]

Description

when using paper-scroll-header-panel with as such <paper-scroll-header-panel main condenses keep-condensed-header header-height="256" condensed-header-height="120">`
on mobile, a blank space is created at the bottom of the screen when the url bar is pushed out of view

Expected outcome

the view should stay consistent without a footer being created

Actual outcome

footer is created

Live Demo

no issue when URL bar is present

When URL bar is pushed off screen it creates a "footer" which cuts object

Steps to reproduce

1.have <paper-scroll-header-panel main condenses keep-condensed-header header-height="256" condensed-header-height="120">`
2. open on mobile device and scroll all the wat down until url bar is pushed out of view then attempt to scroll up

Browsers Affected

• Chrome
• Firefox
• Safari 9
• Safari 8
• Safari 7
• Edge
• IE 11
• IE 10