code: func (remote *RemoteDebugger) SetVisibleSize(width, height int) error {
  	_, err := remote.SendRequest("Emulation.setVisibleSize", Params{
  		"width":  float64(width),
  		"height": float64(height),
  	})
  
  	return err
  }
docs: // SetVisibleSize resizes the frame/viewport of the page.
  // Note that this does not affect the frame's container (e.g. browser window).
  // Can be used to produce screenshots of the specified size.