code: func (c *CSS) GetBackgroundColorsWithParams(v *CSSGetBackgroundColorsParams) ([]string, string, string, error) {
  	resp, err := gcdmessage.SendCustomReturn(c.target, c.target.GetSendCh(), &gcdmessage.ParamRequest{Id: c.target.GetId(), Method: "CSS.getBackgroundColors", Params: v})
  	if err != nil {
  		return nil, "", "", err
  	}
  
  	var chromeData struct {
  		Result struct {
  			BackgroundColors   []string
  			ComputedFontSize   string
  			ComputedFontWeight string
  		}
  	}
  
  	if resp == nil {
  		return nil, "", "", &gcdmessage.ChromeEmptyResponseErr{}
  	}
  
  	// test if error first
  	cerr := &gcdmessage.ChromeErrorResponse{}
  	json.Unmarshal(resp.Data, cerr)
  	if cerr != nil && cerr.Error != nil {
  		return nil, "", "", &gcdmessage.ChromeRequestErr{Resp: cerr}
  	}
  
  	if err := json.Unmarshal(resp.Data, &chromeData); err != nil {
  		return nil, "", "", err
  	}
  
  	return chromeData.Result.BackgroundColors, chromeData.Result.ComputedFontSize, chromeData.Result.ComputedFontWeight, nil
  }
docs: // GetBackgroundColorsWithParams -
  // 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').