diff --git a/popmon/config.py b/popmon/config.py
index c9d90261..c7cf86b1 100644
--- a/popmon/config.py
+++ b/popmon/config.py
@@ -96,7 +96,7 @@ class HistogramSectionModel(SectionModel):
     top_n: int = 20
     """plot heatmap for top 'n' categories. default is 20 (optional)"""
 
-    cmap: str = "autumn_r"
+    cmap: str = "ylorrd"
     """colormap for histogram heatmaps"""
 
 
diff --git a/popmon/pipeline/report_pipelines.py b/popmon/pipeline/report_pipelines.py
index eb13fc9f..b8edf65c 100644
--- a/popmon/pipeline/report_pipelines.py
+++ b/popmon/pipeline/report_pipelines.py
@@ -251,7 +251,9 @@ def __init__(
                 settings=settings,
             ),
             # generate report
-            ReportGenerator(read_key=sections_key, store_key=store_key, settings=settings),
+            ReportGenerator(
+                read_key=sections_key, store_key=store_key, settings=settings
+            ),
         ]
         if (
             isinstance(settings.report_filepath, (str, Path))
diff --git a/popmon/visualization/histogram_section.py b/popmon/visualization/histogram_section.py
index eb587003..7351544c 100644
--- a/popmon/visualization/histogram_section.py
+++ b/popmon/visualization/histogram_section.py
@@ -263,7 +263,6 @@ def _plot_histograms(feature, date, hc_list, hist_names, top_n, max_nbins=1000):
     }
 
 
-
 def _plot_heatmap(
     feature,
     date,
diff --git a/popmon/visualization/report_generator.py b/popmon/visualization/report_generator.py
index aaf643f8..1c7e22b4 100644
--- a/popmon/visualization/report_generator.py
+++ b/popmon/visualization/report_generator.py
@@ -21,6 +21,7 @@
 import htmlmin
 
 from ..base import Module
+from ..config import Report
 from ..resources import templates_env
 from ..version import version
 
@@ -33,7 +34,7 @@ class ReportGenerator(Module):
     _input_keys = ("read_key",)
     _output_keys = ("store_key",)
 
-    def __init__(self, read_key, store_key, online_report=False):
+    def __init__(self, read_key, store_key, settings: Report):
         """Initialize an instance of ReportGenerator.
 
         :param str read_key: key of input sections data to read from the datastore
@@ -43,7 +44,7 @@ def __init__(self, read_key, store_key, online_report=False):
         super().__init__()
         self.read_key = read_key
         self.store_key = store_key
-        self.online_report = online_report if online_report is not None else False
+        self.online_report = settings.online_report
 
     def get_description(self):
         return "HTML Report"
diff --git a/popmon/visualization/utils.py b/popmon/visualization/utils.py
index fc75ebf3..09c0e8d6 100644
--- a/popmon/visualization/utils.py
+++ b/popmon/visualization/utils.py
@@ -22,7 +22,6 @@
 import logging
 import math
 from collections import defaultdict
-from io import BytesIO, StringIO
 from typing import List
 
 import numpy as np