Scroll to bottom of guides page causes page flicker bug

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Expected result

Page should not flicker/jump around

Actual result

The page jumps around and "flickers".

Steps to reproduce

1. Launch https://donejs.github.io/donejs-next/Guides.html
2. Make sure your browser window is at least 1000px wide
3. Scroll to bottom of the page
4. Slowly move cursor from the bottom of the page upwards

Notes

The bug is exhibited in Chrome, Firefox, and Safari. Chrome is bar far the worst. This seems to be the only page affected.