Unify dropdown styles for st.selectbox, st.multiselect, and st.date_input

[jrieke]

Checklist

• I have searched the existing issues for similar feature requests.
• I added a descriptive title and summary to this issue.

Summary

These elements all use slightly different dropdown styles and we should unify.

st.selectbox:

st.multiselect – almost the same as selectbox but the dropdown is a bit higher and overlaps the element slightly:

st.date_input – this one looks completely different, both spacing and shadow are different:

When doing this, we should probably also have a look at other elements that have a dropdown and make sure they are all consistent.

Why?

Consistency 😉

How?

No response

Additional Context

No response

[github-actions]

To help Streamlit prioritize this feature, react with a 👍 (thumbs up emoji) to the initial post.

Your vote helps us identify which enhancements matter most to our users.