Use white background for text/html result

[garaemon]

• Use white background to increase visibility of the GUI icons on dark UI themes.

Before applying this change:

After applying this change:

test code from mpld3 example code

import matplotlib.pyplot as plt
import numpy as np
import pandas as pd
import mpld3
from mpld3 import plugins
mpld3.enable_notebook()
np.random.seed(9615)

# generate df
N = 100
df = pd.DataFrame((.1 * (np.random.random((N, 5)) - .5)).cumsum(0),
                  columns=['a', 'b', 'c', 'd', 'e'],)

# plot line + confidence interval
fig, ax = plt.subplots()
ax.grid(True, alpha=0.3)

for key, val in df.iteritems():
    l, = ax.plot(val.index, val.values, label=key)
    ax.fill_between(val.index,
                    val.values * .5, val.values * 1.5,
                    color=l.get_color(), alpha=.4)

# define interactive legend

handles, labels = ax.get_legend_handles_labels() # return lines and labels
interactive_legend = plugins.InteractiveLegendPlugin(zip(handles,
                                                         ax.collections),
                                                     labels,
                                                     alpha_unsel=0.5,
                                                     alpha_over=1.5,
                                                     start_visible=True)
plugins.connect(fig, interactive_legend)

ax.set_xlabel('x')
ax.set_ylabel('y')
ax.set_title('Interactive legend', size=20)
fig.patch.set_facecolor('blue')
fig.patch.set_alpha(1.0)
mpld3.display()

[ghost]

Would it be possible to limit the white background to the plotting area only? So it does not stretch too much to the right side? Think it will look much better if it is limited.