Hi there,
there are not specific settings rather then than enabling the Snews Option > Backgrounds > Dark Color Palette after setting a dark color palette (this will adjust opacity layers).

If what you're seeking for are the exact color values from the live demo, here they are:

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PRIMARY BACKGROUND COLOR: #222222

SECONDARY BACKGROUND COLOR: #000000

ACCENT COLOR: #333333

SET A BACKGROUND COLOR OR PATTERN: #222222

NAVIGATION BACKGROUND: #252525

CARDS BACKGROUND: #171717

CARDS TITLES BACKGROUND: #000000

CARDS BORDER COLOR: #111111

CARDS BORDER TOP COLOR: #000000

CARDS TOP BORDER WIDTH: 8px

DARK COLOR PALETTE?: On

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Hope it helps