Problem with chart annotations on save

plotly.js
1

I am creating a bar chart with an annotation positioned on paper at 0,-025
The code

		annotations : [{text :  'Data and Visualization by  Colorado State Demography Office.  Print Date: ' +  fmt_date(new Date) , 
 				font: {
				size: 6,
				color: 'black'
			   },
			   xref : 'paper',
		   x : 0, 
		   yref : 'paper', 
		   y :  -0.20,
		   align : 'left', 
		   showarrow : false}]
	};

Here is the chart on my webpage:

image
image1253×487 20.6 KB

This code puts the source citation right under the y-axis, where I want it. However, when I save the file as a png, the annotation is lower on the plot. For example:

Population Forecast Colorado (2)
Population Forecast Colorado (2)1000×500 22.5 KB

Here is the code I used to save the Plotly Image:

	   Plotly.toImage(graphDiv, { format: 'png', width: 1000, height: 500 }).then(function (dataURL) {
        var a = document.createElement('a');
        a.href = dataURL;
        a.download = fn;
        document.body.appendChild(a);
         a.click();
        document.body.removeChild(a);
    });

where “graphDiv” is the web page div that contains the plot.

Is there a way to make sure the annotations are output in the same position in the saved image as in the online image?