Shading a background a specific color

Trying to add a red shaded area to part of the background of the chart, that extends from the bottom edge to the zeroline. I know the y value is wrong, which is why the shading area looks funny. Wondering if someone can help here and make some suggestions about how to handle y value so that it creates a fixed value that covers the entire graph.

Here’s the code, and and an image of what it looks like so far.

fig.add_trace(go.Scatter(x=self.distmin['variable'], y=self.distmin['value'],fill='tozeroy',line=dict(width=0),fillcolor='red',showlegend=False))