# Panel 5 Twin Axis 0-Alignment

## Problem
In ETF monitor Panel 5 (stacked flow + daily change rate%), the left axis (日净变动 亿元) and right axis 1 (日变动率 %) use `twinx()`, so they auto-scale independently. Their zero lines don't align, creating visual confusion.

## Solution
After plotting both axes but before creating the third twinx axis, adjust right axis 1's ylim so its zero matches the left axis zero position:

```python
# Insert after ax_flow2.tick_params(...) and before ax_flow3 = ax_flow.twinx()
ymin1, ymax1 = ax_flow.get_ylim()
ymin2, ymax2 = ax_flow2.get_ylim()
range1 = ymax1 - ymin1
range2 = ymax2 - ymin2
if range1 > 0 and range2 > 0:
    pos_ratio = ymax1 / range1  # 0's fractional position on left axis (0~1)
    ax_flow2.set_ylim(-(1 - pos_ratio) * range2, pos_ratio * range2)
```

## How It Works
- `pos_ratio` = where 0 sits on the left axis (e.g., 0.55 = 55% from bottom)
- Right axis range (`range2`) is preserved, but split at the same ratio
- Left 0 at 55% → right 0 also at 55%

## Applied To
All four monitor scripts (identical patch):
- `national_team_monitor.py` (line ~445)
- `tech_etf_monitor.py` (line ~444)
- `old_economy_etf_monitor.py` (line ~430)
- `gold_etf_monitor.py` (line ~430)

## Verification
Before alignment: left 0 at 55.1%, right 0 at 54.0% (visible gap).
After alignment: both at same position.

## Note
The third twinx axis (合计净资产, ax_flow3) is not affected since it has its own independent scale and doesn't need 0-alignment.