Checklist

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Summary

We already support several Markdown extensions, e.g. to write colored text via st.markdown(":red[foo]"). What if we did the same thing for small text, e.g. via st.markdown(":small[foo]")?

Why?

This can be used for several cool things:

• Replicate the same styling as widget labels outside of a widget. This is especially helpful if you put a widget and another element next to each other. Today, you can't get the same style as a widget label because st.markdown is too big and st.caption is gray.
• Making small badges via :small[:orange-background[:orange[tag]]].
• Using big and small text in the same element, e.g. for the badges in our roadmap app.

How?

Just add a new Markdown extension, similar to the one for colored text. We should make sure all these extensions also work together properly.

Potentially, we could also make st.caption simply be st.markdown(":small[:gray[foo]]") then! Even though today st.caption uses a slightly different gray than colored text.

Additional Context

No response