How can I create borders around containers?

How can I make colored borders of specified thickness appear around containers? E.g.

secondrow1, secondrow2, secondrow3, secondrow4 = st.columns([3,2,4,4])
secondrow1title = "**" + 'Public domain books in progress:** (' + str(len(public_domain_files)) + ')'
secondrow1.markdown(secondrow1title)
with secondrow1.container(): # I want a border around this container
    with st.form(key="PublicDomainBooks"):
        selected_file = secondrow1.selectbox("Select a file to work on:", public_domain_files)
        submitted = st.form_submit_button("Work on this file")
        if submitted:
            run_this_file = os.path.join(public_domain_path, selected_file)
            subprocess.call(['open',run_this_file])

with secondrow2.container():  # I want a border around this container
    with st.form("Contracted Titles In Progress"):
        st.markdown("**Royaltied Titles With Duty to Publish:**")
        contracted_files = get_filenames(contracted_path)
        selected_file = st.selectbox("Select a file to work on:", contracted_files)
        submitted = st.form_submit_button("Work on this file")
        if submitted:
            run_this_file = os.path.join(public_domain_path, selected_file)
            subprocess.call(['open',run_this_file])