code: func (c *CSS) GetBackgroundColors(nodeId int) ([]string, string, string, error) {
  	var v CSSGetBackgroundColorsParams
  	v.NodeId = nodeId
  	return c.GetBackgroundColorsWithParams(&v)
  }
docs: // GetBackgroundColors -
  // nodeId - Id of the node to get background colors for.
  // Returns -  backgroundColors - The range of background colors behind this element, if it contains any visible text. If no visible text is present, this will be undefined. In the case of a flat background color, this will consist of simply that color. In the case of a gradient, this will consist of each of the color stops. For anything more complicated, this will be an empty array. Images will be ignored (as if the image had failed to load). computedFontSize - The computed font size for this node, as a CSS computed value string (e.g. '12px'). computedFontWeight - The computed font weight for this node, as a CSS computed value string (e.g. 'normal' or '100').