Custom background-color of selectbox elements

Hello guys,

I am trying to have a st.selectbox() where I am able to change the background color of specific items.

However, I do not want this to be applied to the other dropdown menus of my streamlit app.

Here is what I was able to do untill now:

import streamlit as st

ex_1 = st.sidebar.multiselect("Anything", ['Anything1', "Anything2", "Anything3"])

div[role="listbox"] li:nth-of-type(1){
    background-color: red;
div[role="listbox"] li:nth-of-type(2){
    background-color: blue;


ex_2 = st.sidebar.multiselect("Something", ['Something1', "Something2", "Something3"])

The problem with this approach is that my css style impacts both of my dropdown menus (ex_1 & ex_2). How would I be able to make it only impact ex_2?

Thanks in advance,