Siberian is a basic Adapt theme that meets WCAG 2.1 AA color contrast.
There are no custom classes added to the theme.
You can download the color pallet (click the image to the right to download) to incorporate the colors into your graphics. The top row of colors are the base theme colors and the lower row of colors are used as accents and for success/failure messaging.
When using the Parallax Articles extension, these color combinations are used for the background and text and will override any general theme settings. This theme contains subtle gradients rather than solid colors.