Cutoff Threshold Light

import matplotlib.pyplot as plt
import numpy as np
from scipy.cluster.hierarchy import dendrogram, linkage, set_link_color_palette

np.random.seed(321)

labels = ['P' + str(i) for i in range(1, 15)]
data = np.random.rand(len(labels), 6) * 70
Z = linkage(data, method='ward')

fig, ax = plt.subplots(figsize=(14, 8), facecolor='#ffffff')
ax.set_facecolor('#ffffff')

cutoff = 0.6 * max(Z[:,2])

set_link_color_palette(['#F5276C', '#27D3F5', '#6CF527', '#F5B027', '#5314E6'])

dn = dendrogram(Z, labels=labels, leaf_rotation=45, leaf_font_size=10,
                color_threshold=cutoff, above_threshold_color='#9ca3af', ax=ax)

# Cutoff line with soft shadow
ax.axhline(y=cutoff, color='#F5276C', linewidth=2, linestyle='--', alpha=0.8)
ax.fill_between([ax.get_xlim()[0], ax.get_xlim()[1]], 0, cutoff, 
                color='#27D3F5', alpha=0.06, zorder=0)

ax.annotate('Cluster Cutoff', xy=(ax.get_xlim()[1]-10, cutoff), 
            color='#F5276C', fontsize=10, va='bottom', fontweight='bold')

ax.set_title('Dendrogram with Cluster Cutoff Threshold', fontsize=15, 
             color='#1f2937', fontweight='bold', pad=20)
ax.set_xlabel('Points', fontsize=11, color='#374151')
ax.set_ylabel('Ward Distance', fontsize=11, color='#374151')
ax.tick_params(axis='both', colors='#374151', labelsize=10)
ax.spines['top'].set_visible(False)
ax.spines['right'].set_visible(False)
ax.spines['left'].set_color('#e5e7eb')
ax.spines['bottom'].set_color('#e5e7eb')

plt.tight_layout()
plt.show()