You can enable the sticky footer and choose its fade color from Theme options > Layout > Footer:
Theme Options > Pages, Blog, Portfolio or Shop > Intro > Custom Top/Bottom Padding
Example of a sticky footer:
https://theme.pixfort.com/onepage/
Note: The sticky footer is only available for the desktop version since normally the footer height will be bigger than the mobile and tablet screen size, so not all the content of the sticky footer will be visible (the content at the beginning of the sticky footer will be off-screen from top and it won’t be accessible).
When enabling the sticky footer option the footer will show as normal footer in the tablet and mobile versions.