Remove border from matplotlib 3D pane

I would like to remove the borders from my 3D scene as described below. Any idea how to do that?

Here the code to generate the current scene:

import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D

# Create figure
plt.style.use('dark_background') # Dark theme
fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')

# Make panes transparent
ax.xaxis.pane.fill = False # Left pane
ax.yaxis.pane.fill = False # Right pane

# Remove grid lines
ax.grid(False)

# Remove tick labels
ax.set_xticklabels([])
ax.set_yticklabels([])
ax.set_zticklabels([])

# Print chart
file_path = 'charts/3d.png'
fig.savefig(file_path, bbox_inches='tight', pad_inches=0.05, transparent=True)

I usually set the alpha channel to 0 for spines and panes, and finally I remove the ticks:

import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D

# Create figure
plt.style.use('dark_background') # Dark theme
fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')

# Make panes transparent
ax.xaxis.pane.fill = False # Left pane
ax.yaxis.pane.fill = False # Right pane

# Remove grid lines
ax.grid(False)

# Remove tick labels
ax.set_xticklabels([])
ax.set_yticklabels([])
ax.set_zticklabels([])

# Transparent spines
ax.w_xaxis.line.set_color((1.0, 1.0, 1.0, 0.0))
ax.w_yaxis.line.set_color((1.0, 1.0, 1.0, 0.0))
ax.w_zaxis.line.set_color((1.0, 1.0, 1.0, 0.0))

# Transparent panes
ax.w_xaxis.set_pane_color((1.0, 1.0, 1.0, 0.0))
ax.w_yaxis.set_pane_color((1.0, 1.0, 1.0, 0.0))

# No ticks
ax.set_xticks([]) 
ax.set_yticks([]) 
ax.set_zticks([])