我希望改变stackplot的调色板，使大面积有一个浅色，小面积有一个明亮的颜色。

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
import seaborn as sns
from scipy.stats import norm
import matplotlib as mpl
import matplotlib.font_manager as font_manager
file = r'E:\FD\Barren_Mudflat\ChinaCoastal\Provinces\0ProvinceStat.csv'
#set font property of legend
font1 = {'family' : 'Times New Roman',  
'weight' : 'normal',  
'size'   : 16
} 
#read csv
dat1 = pd.read_csv(file)
dat2 = dat1.iloc[:,0:12]
Year = dat2.iloc[:,0]
Mud = dat2.iloc[:,1:12]
Mud = Mud/1000.0
#read columns of dataframe
vol = Mud.columns
#transpose mud
mud2 = Mud.T
%matplotlib qt5
#set size of figure
fig, ax = plt.subplots()
fig.set_size_inches(15, 7.5)
#read values of dataframe
value = mud2.values
#plot stack area
sp = ax.stackplot(Year, value)
#set legend
proxy = [mpl.patches.Rectangle((0,0), 0,0, facecolor=pol.get_facecolor()[0]) 
for pol in sp]
ax.legend(proxy, vol,prop = font1, loc='upper left', bbox_to_anchor= 
(0.01,1), ncol = 6)
plt.xlim(1986,2016)
plt.xticks([1986,1991,1996,2001,2006,2011,2016],fontproperties='Times New 
Roman', size = '16')
plt.xlabel('Year',fontproperties='Times New Roman', size = '18')
plt.ylim(0,1400)
plt.yticks(np.arange(0,1500,200),fontproperties='Times New Roman', size = 
'16')
plt.ylabel('Mudflat area (thousand ha)',fontproperties='Times New Roman', 
size = '18')
#save fig: run this code before show()
plt.savefig(r"E:\FD\Barren_Mudflat\ChinaCoastal\Provinces\stackplot.jpg", 
dpi = 600)
plt.show()

这是代码的结果，我希望把红色改成浅色，但是不知道怎么改默认颜色