You can inject HTML, CSS & JavaScript through multiple methods, most commonly the st.markdown():
st.markdown("""
some streamlit class name {
background: red;
}
""", unsafe_allow_html=True)
You can do the same with javascript if you can get the classes names etc or inject it within an HTML component, for this I redirect you to this question I just answerd where you can find how to add whole HTML comonents or just iframes: