[Python] How to resize/fit Altair chart in Quarto dashboard container?

The Quarto docs state that Altair charts resize themselves to fit their container within dashboards.

My experience is that this is true for alt.Chart(), but not if I concatenate multiple charts via alt.hconcat().

---
title: "Test"
format: dashboard
---

```{python}
#| title: alt.chart()

import altair as alt
from vega_datasets import data
source = data.iowa_electricity()
alt.Chart(source).mark_area(opacity=0.3).encode(
x="year:T",
y=alt.Y("net_generation:Q").stack(None),
color="source:N"
)
```

```{python}
#| title: Chart concatenation

import altair as alt
from vega_datasets import data
source = data.iowa_electricity()
chart1 = alt.Chart(source).mark_area(opacity=0.3).encode(
x="year:T",
y=alt.Y("net_generation:Q").stack(None),
color="source:N"
)

chart2 = alt.Chart(source).mark_area(opacity=0.3).encode(
y="year:T",
x=alt.Y("net_generation:Q").stack(None),
color="source:N"
)

alt.hconcat(chart1, chart2)
```




Is there a way to fit a concatenated chart to its container?

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