Line with different negative color
Axis ranges
Axis ranges allow defining a scope of values, or a stretch between categories, or dates. Any property of the segment of the series that falls into that range can be overridden.
This demo shows how we can color any segment of the line below the zero line with an alternative color.
More about using axis ranges with series
Date axis
Date axis is perfect for depicting date/time-based data on a natural scale.