Plotly: scatter conditional color formatting issues

Any idea why the conditional color formatting isn't working here when the mode = 'lines' is activated ?

import plotly.offline as py
import plotly.graph_objs as go
from plotly.offline import init_notebook_mode, iplot, plot
from plotly import tools
import pandas as pd
import numpy
init_notebook_mode(connected=True)

data = [
    [1, 0.5, True],
    [2, 0.7, True],
    [3, -0.1, False],
    [4, -0.3, False],
    [5, -0.5, False],
]

df = pd.DataFrame(
    data,
    columns=['x', 'y', 'Above 0']
)

trace = go.Scatter(
    x=df['x'],
    y=df['y'],
    #mode='markers',  
    mode='lines',     #<---  ISSUE HERE. #########################################
    marker=dict(
        # I want the color to be green if 
        # lower_limit ≤ y ≤ upper_limit
        # else red
        color=np.where(df['Above 0'], 'green', 'red'),
    )
)


iplot([trace])

The final idea is to plot an oscilliator arround 0 that forward fill green above 0 and red below 0.

Like so: enter image description here

given what you are looking to achieve. Green filled above zero and red filled below zero, two traces
have used plotly express instead of graph objects to simplify code
have used https://numpy.org/doc/stable/reference/generated/numpy.interp.html to expand out points so that y==0 switch over is within data set

import pandas as pd
import numpy as np
import plotly.graph_objects as go
import plotly.express as px

data = [
    [1, 0.5, True],
    [2, 0.7, True],
    [3, -0.1, False],
    [4, -0.3, False],
    [5, -0.5, False],
]

df = pd.DataFrame(data, columns=["x", "y", "Above 0"])

# interpolate out line so that when it goes across y=0 gap is minimised
xn = np.linspace(df["x"].min(), df["x"].max(), len(df) * 25)
df2 = pd.DataFrame({"x": xn, "y": np.interp(xn, df["x"], df["y"])})

px.line(
    df2,
    x="x",
    y="y",
    color=df2["y"] > 0,
    color_discrete_map={True: "green", False: "red"},
).update_traces(fill="tozeroy", showlegend=False)

enter image description here