I'm trying to create a bar chart which has both positive and negative X-axis values (X-axis values range from -15 to +20). I see how you can invert the colors of the bars depending on whether the Y values is negative, but I cannot find how to do this when the X value is negative. The scenario here is I'm charting the frequency of arrival times relative to a fixed time (zero) so negative values are early and positive values are late. I'd like to color the columns that are late a different color so they stand out. I'm using Excel 2010