Constant charts::AXIS_LABEL_MARGIN

pub const AXIS_LABEL_MARGIN: usize = 12;

The top-and/or-bottom margin of x-axis labels and the right-and/or-left margin of y-axis labels.

x-axis labels always have top margin. If the x-axis title is N/A, x-axis labels also have bottom margin.

y-axis labels always have right margin. If the y-axis title is N/A, y-axis labels also have left margin.