issue with run : 'button_style' is not defined

[Mahantor]

NameError: name 'button_style' is not defined
Traceback:
File "C:\ProgramData\anaconda3\Lib\site-packages\streamlit\runtime\scriptrunner\exec_code.py", line 85, in exec_func_with_error_handling
result = func()
^^^^^^
File "C:\ProgramData\anaconda3\Lib\site-packages\streamlit\runtime\scriptrunner\script_runner.py", line 576, in code_to_exec
exec(code, module.dict)
File "C:\Users\SaeID\Desktop\VideoLingo\st.py", line 123, in
main()
File "C:\Users\SaeID\Desktop\VideoLingo\st.py", line 112, in main
st.markdown(button_style, unsafe_allow_html=True)
^^^^^^^^^^^^