Font size cannot change in my picture

I'm trying to draw a radar char using pygal. however, I found the way to change font size of labels not work, even I put all font size related attribute. And below paste my code.

import pygal
from IPython.display import Image, SVG
from pygal.style import LightStyle, CleanStyle, Style

custom_style = Style(
    background='transparent',
    plot_background='transparent',
    foreground='black',
    foreground_strong='black',
    foreground_subtle='#630C0D',
    opacity='.3',
    colors=('red', 'green', 'blue', ))

radar_chart = pygal.Radar(width=420, height=400, show_legend=False, fill=True,
                          legend_font_size = 40.0,
                          value_font_size = 40.0,
                          tooltip_font_size = 40.0,
                          major_label_font_size = 40.0,
                          label_font_sioze = 40.0,
                          value_label_font_size = 40.0,
                          margin=5, show_dots=False, style=custom_style, )

radar_chart.title = 'TITLE'
radar_chart.x_labels = ['Richards', 'DeltaBlue', 'Crypto', 'RayTrace', 'EarleyBoyer', 'RegExp', 'Splay', 'NavierStokes']
radar_chart.add('Chrome', [6395, 8212, 7520, 7218, 12464, 1660, 2123, 8607])
radar_chart.add('Firefox', [7473, 8099, 11700, 2651, 6361, 1044, 3797, 9450])
radar_chart.add('Opera', [3472, 2933, 4203, 5229, 5810, 1828, 9013, 4669])
# radar_chart.add('IE', [43, 41, 59, 79, 144, 136, 34, 102])
radar_chart.render_to_png("./image_pygal/radar.png")

Image(filename="./image_pygal/radar.png")

Start with the shown pygal.Radar configuration and check each font-size argument, especially the misspelled label_font_sioze, against pygal's accepted names. Render radar.png again and verify that the intended chart labels reflect the configured font sizes.