Checklist

• I have searched the existing issues for similar issues.
• I added a very descriptive title to this issue.
• I have provided sufficient information below to help reproduce this issue.

Summary

As of 1.21.0, the configuration setting of theme.font is being applied to code blocks. This was not the behavior in 1.20.0 (and earlier), and is directly contradicted by the configuration documentation which pretty explicitly states that this setting is to set the

Font family for all text in the app, except code blocks.

Reproducible Code Example

import streamlit as st

if st.session_state.setdefault("_first_run", True):
    # Ensure we're starting from a clean slate for this test
    st.config.set_option("theme.font", None)
    st.session_state._first_run = False
    st.experimental_rerun()

st.write("Font setting (if any): ", st.config.get_option("theme.font"))
st.code('{"key": "value"}', language="json")

if st.button("Set font to sans serif"):
    st.config.set_option("theme.font", "sans serif")
    st.experimental_rerun()

Steps To Reproduce

1. Run sample and observe visual appearance of code block
2. Click "Set font to sans serif" button to set the script font to "sans serif"
3. Observe the different font being applied to the code block

Expected Behavior

theme.font setting is not applied to code blocks

Current Behavior

theme.font setting is applied to code blocks

Is this a regression?

• Yes, this used to work in a previous version.

Debug info

• Streamlit version: 1.21.0
• Python version: 3.9.16 and 3.11.0
• Operating System: Ubuntu 22.04.2
• Browser: Chrome 111.0.5563.146
• Virtual environment: venv

Additional Information

For awareness, there is another documented issue related to code blocks in 1.21.0. I suspect this issue may relate to that one, but I'm not 100% certain that that is the case.

Are you willing to submit a PR?

• Yes, I am willing to submit a PR!