Can't color the column headers css in the data

Using Streamlit
1

I am creating a test version of an application. I receive a csv file and want to render it. I have fields that are immutable and some that are mutable. I would like to color the column headers green for immutable and blue for mutable. But the problem is that I can’t color the headers at all, in any way.
i try to do something this
def highlight_headers():
return “”"

table thead th {
background-color: black !important;
color: black !important;
text-align: center !important;
}

“”"

    st.markdown(highlight_headers(), unsafe_allow_html=True)

    st.dataframe(df)