st.map is narrow inside expander unless another map is added

[blackary]

Checklist

• I have searched the existing issues for similar issues.
• I added a very descriptive title to this issue.
• I have provided sufficient information below to help reproduce this issue.

Summary

If I add a map inside an expander, it is fairly narrow. If I add a second map and refresh the page, it expands to the full container width.

Reproducible Code Example

import streamlit as st
import pandas as pd

d = {"lat": [40.781243], "lon": [-73.968432]}

df = pd.DataFrame.from_dict(d)

with st.expander("map"):
    st.map(df, size=2)

if st.checkbox("Add extra map"):
    st.map(df, size=2)

Steps To Reproduce

Expand the expander, and note that the map is narrow

Click the checkbox to show another map

Hit r to refresh the app

Expected Behavior

The app should be full width

Current Behavior

No response

Is this a regression?

• Yes, this used to work in a previous version.

Debug info

• Streamlit version: 1.30.0
• Python version: 3.10.3
• Operating System: Mac OS
• Browser: Chrome

Additional Information

Reported on https://discuss.streamlit.io/t/st-map-does-not-display-properly-inside-expander/60316?u=blackary

[github-actions]

If this issue affects you, please react with a 👍 (thumbs up emoji) to the initial post.

Your feedback helps us prioritize which bugs to investigate and address first.

[LukasMasuch]

@blackary Thanks for reporting this issue. I reproduced this here. Even if use_container_width=True is set, it's not using the full available size. Seems like a bug or even a regression (related to #7113 / #7307).