Basic Stackplot

import matplotlib.pyplot as plt
import numpy as np

COLORS = {
    'layers': ['#6366F1', '#10B981', '#F59E0B'],
    'background': '#FFFFFF',
    'text': '#1E293B',
    'text_muted': '#64748B',
    'grid': '#F1F5F9'
}

x = np.arange(0, 10, 1)
y1 = [1, 1.25, 2, 2.75, 3, 3.5, 4, 4.2, 4.5, 5]
y2 = [1, 1, 1, 1, 1, 1.2, 1.3, 1.4, 1.5, 1.6]
y3 = [2, 1.8, 2, 1.5, 2, 2.2, 1.8, 2.1, 2.3, 2.5]

fig, ax = plt.subplots(figsize=(10, 6), dpi=100)
ax.set_facecolor(COLORS['background'])
fig.patch.set_facecolor(COLORS['background'])

ax.stackplot(x, y1, y2, y3, colors=COLORS['layers'], alpha=0.85, 
             labels=['Series A', 'Series B', 'Series C'])

ax.spines['top'].set_visible(False)
ax.spines['right'].set_visible(False)
ax.spines['left'].set_color(COLORS['grid'])
ax.spines['bottom'].set_color(COLORS['grid'])
ax.tick_params(axis='both', colors=COLORS['text_muted'], labelsize=9, length=0, pad=8)
ax.set_xlim(0, 9)
ax.set_ylim(0, 10)
ax.legend(loc='upper center', bbox_to_anchor=(0.5, -0.10), ncol=3, frameon=False, fontsize=9, labelcolor=COLORS['text_muted'])

plt.tight_layout()
plt.show()