HighCharts - Change tooltip font size

HighCharts - Change tooltip font size

I'm trying to use the AdvancedFormat_Init function to set the font for my tooltip.  The default is too big.  I'm passing the following which I got from the HighCharts_API documentation.

"tooltip: {
            useHTML: true,
            headerFormat: '<small>{point.key}</small>'
I'm sure I'm missing some syntax to make it proper JSON I just don't know what it is.

Thanks in advance,

I was able to figure this out after a while.  The Advanced Format syntax to change the font size for the tooltip on a chart is:

"tooltip: { style: {fontSize: '7pt'} }"
Hope that helps someone.