Waterfall chart with scale=alt.Scale(domain=[2000, 8000])

[SeeBastion524]

I used the example from the Gallery for the waterfall chart. When I add scale=alt.Scale(domain=[2000, 8000]) the bars will overlap with the axis. Here is the complete code:

import altair as alt
import pandas as pd

data = [
{"label": "Begin", "amount": 4000},
{"label": "Jan", "amount": 1707},
{"label": "Feb", "amount": -1425},
{"label": "Mar", "amount": -1030},
{"label": "Apr", "amount": 1812},
{"label": "May", "amount": -1067},
{"label": "Jun", "amount": -1481},
{"label": "Jul", "amount": 1228},
{"label": "Aug", "amount": 1176},
{"label": "Sep", "amount": 1146},
{"label": "Oct", "amount": 1205},
{"label": "Nov", "amount": -1388},
{"label": "Dec", "amount": 1492},
{"label": "End", "amount": 0},
]
source = pd.DataFrame(data)

Define frequently referenced fields

amount = alt.datum.amount
label = alt.datum.label
window_lead_label = alt.datum.window_lead_label
window_sum_amount = alt.datum.window_sum_amount

Define frequently referenced/long expressions

calc_prev_sum = alt.expr.if_(label == "End", 0, window_sum_amount - amount)
calc_amount = alt.expr.if_(label == "End", window_sum_amount, amount)
calc_text_amount = (
alt.expr.if_((label != "Begin") & (label != "End") & calc_amount > 0, "+", "")
+ calc_amount
)

The "base_chart" defines the transform_window, transform_calculate, and X axis

base_chart = alt.Chart(source).transform_window(
window_sum_amount="sum(amount)",
window_lead_label="lead(label)",
).transform_calculate(
calc_lead=alt.expr.if_((window_lead_label == None), label, window_lead_label),
calc_prev_sum=calc_prev_sum,
calc_amount=calc_amount,
calc_text_amount=calc_text_amount,
calc_center=(window_sum_amount + calc_prev_sum) / 2,
calc_sum_dec=alt.expr.if_(window_sum_amount < calc_prev_sum, window_sum_amount, ""),
calc_sum_inc=alt.expr.if_(window_sum_amount > calc_prev_sum, window_sum_amount, ""),
).encode(
x=alt.X("label:O", axis=alt.Axis(title="Months", labelAngle=0), sort=None)
)

color_coding = (
alt.when((label == "Begin") | (label == "End"))
.then(alt.value("#878d96"))
.when(calc_amount < 0)
.then(alt.value("#fa4d56"))
.otherwise(alt.value("#24a148"))
)

bar = base_chart.mark_bar(size=45).encode(
y=alt.Y("calc_prev_sum:Q", title="Amount", scale=alt.Scale(domain=[2000, 8000])),
y2=alt.Y2("window_sum_amount:Q"),
color=color_coding,
)

The "rule" chart is for the horizontal lines that connect the bars

rule = base_chart.mark_rule(xOffset=-22.5, x2Offset=22.5).encode(
y="window_sum_amount:Q",
x2="calc_lead",
)

Add values as text

text_pos_values_top_of_bar = base_chart.mark_text(baseline="bottom", dy=-4).encode(
text=alt.Text("calc_sum_inc:N"),
y="calc_sum_inc:Q",
)
text_neg_values_bot_of_bar = base_chart.mark_text(baseline="top", dy=4).encode(
text=alt.Text("calc_sum_dec:N"),
y="calc_sum_dec:Q",
)
text_bar_values_mid_of_bar = base_chart.mark_text(baseline="middle").encode(
text=alt.Text("calc_text_amount:N"),
y="calc_center:Q",
color=alt.value("white"),
)

alt.layer(
bar,
rule,
text_pos_values_top_of_bar,
text_neg_values_bot_of_bar,
text_bar_values_mid_of_bar
).properties(
width=800,
height=450
)

Any suggestions?