Styling a specific "container" with a specific "div class"

[krmyldrm]

Hello i have just started using Streamlit. I want to style a specific “container” with a specific “div class” but I have a problem.

This is my py code:

import streamlit as st

def local_css(file_name):
    with open(file_name) as f:
        st.markdown(f'<style>{f.read()}</style>', unsafe_allow_html=True)

container1 = st.container()
div = """<div class = 'test1'>"""
divEnd = """</div>"""

container2 = st.container()

with container1:
    container1.markdown(div, unsafe_allow_html=True)
    st.header("Hello")
    container1.markdown(divEnd, unsafe_allow_html=True)

with container2:
    st.header("Hello2")

local_css("style.css")

This is my css:

.test1 {
    background-color: black;
    border: 1px solid #DCDCDC;
    padding: 20px 20px 20px 70px;
    padding: 5% 5% 5% 10%;
    border-radius: 10px;
}

A picture from my program:

Why the “Hello” header is not in container1? Can you help me

Python version: 3.12.3
Streamlit version: 1.34.0