The BackgroundBlendMode property in the Sandbox.UI.BaseStyles class represents the background-blend-mode CSS property. This property is used to define the blending mode for each background layer of an element. It determines how the background image should blend with the background color or other background images.

To use the BackgroundBlendMode property, assign it a string value that corresponds to a valid CSS blend mode. Common values include normal, multiply, screen, overlay, and others as defined in the CSS specification.