What is wrong here in colouring the Excel sheet?

Question

Here I need to colour 'red' for rows with Age<13 and colur 'green' for rows with Age>=13. But the final 'Report.xlsx' isn't getting coloured. What is wrong here?

import pandas as pd

data = [['tom', 10], ['nick', 12], ['juli', 14]]

df = pd.DataFrame(data, columns = ['Name', 'Age'])

df_styled = df.style.applymap(lambda x: 'background:red' if x < 13 else 'background:green', subset=['Age'])

df_styled.to_excel('Report.xlsx',engine='openpyxl',index=False)