Problem with chart annotations on save

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:

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:

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; = fn;

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?