Excel 2007 : Chart lines are too thick using default templates and Pivot table/chart

Hello everyone, hope someone here can help.

Although I have no problem cycling through my chart lines and chaning the thickness (there's a fair few series of data here) I need to provide this chart to a client who will then be able to select pivot chart data and it will automatically chart the relevant lines.

Currently any additional series I plot doesn't retain the chart style of the previous lines.

I need the 'Chart style' to have the differing colours (as it is by default) but with a much lower line thickness (due to the proximity of the data points in places I'm using 0.25pt line thickness)

any ideas?