Create Excel line chart with dynamic red/green line based on zero value

I am looking for an experienced Excel freelancer to build a **reusable Excel template (.xlsx)** with a line chart that changes color based on the value relative to zero:

* **Red** for values/segments **below 0**
* **Green** for values/segments **at or above 0**

The chart should visually match the attached example (smooth and clean), and it must update automatically when the input values are changed.

### Scope

* Create a working Excel chart solution using standard Excel functionality
* Support a typical monthly dataset (Jan–Dec), but the setup should be easy to reuse
* Ensure the color split follows the zero line dynamically (including transitions across zero)

### Technical preferences

* **Formula-based solution preferred** (with helper columns/series if needed)
* VBA/macros only if necessary (please explain why)
* Clean structure so the file is easy to maintain and reuse

### Deliverables

1. Final Excel file (.xlsx) with chart fully configured
2. Short documentation (sheet note or comments) explaining:

* where to enter/update data
* how the chart works (at a high level)
* how to reuse the template for another dataset

### Please include in your proposal

* Relevant experience with advanced Excel charts / conditional chart formatting
* Which Excel version you will build/test in
* Fixed price and delivery time
* A short explanation of your proposed approach (e.g., helper series, formulas, chart setup)

I will attach a screenshot showing the exact visual style I want.

Please confirm that the line is split correctly at zero crossing (not only point color).