diff --git a/parameters.yaml b/parameters.yaml
index 68b9b9d..7821e3c 100644
--- a/parameters.yaml
+++ b/parameters.yaml
@@ -128,7 +128,7 @@ add_global_links:
   - {"text": "show recent events on map",
      "URL": "https://fdsnws.geophysik.ruhr-uni-bochum.de/map/?lat=39.5&lon=21&zoom=7&baselayer=mapnik"}
 
-# html logo at page bottom
+# html logo at page bottom (path relative to html directory)
 html_logo: "figures/Logo_RUB_BLAU_rgb.png"
 
 # E-mail notifications
diff --git a/survBot.py b/survBot.py
index 261965a..2a06ac2 100755
--- a/survBot.py
+++ b/survBot.py
@@ -503,12 +503,21 @@ class SurveillanceBot(object):
 
                 outfile.write(finish_html_table())
 
+                # add optional links below html table
                 for dct in self.add_global_links:
                     link_str = get_html_link(dct.get('text'), dct.get('URL'))
                     outfile.write(get_html_text(link_str))
 
+                # add status message
                 outfile.write(get_html_text(self.status_message))
-                outfile.write(html_footer(footer_logo=self.parameters.get('html_logo')))
+
+                # write footer with optional logo
+                logo_file = self.parameters.get('html_logo')
+                if not os.path.isfile(logo_file):
+                    print(f'Specified file {logo_file} not found.')
+                    logo_file = None
+
+                outfile.write(html_footer(footer_logo=logo_file))
 
         except Exception as e:
             print(f'Could not write HTML table to {fnout}:')
diff --git a/utils.py b/utils.py
index 2168c01..a34de20 100644
--- a/utils.py
+++ b/utils.py
@@ -35,10 +35,10 @@ def get_bg_color(check_key, status, dt_thresh=None, hex=False):
 
 def get_color(key):
     # some GUI default colors
-    colors_dict = {'FAIL': (255, 50, 0, 255),
+    colors_dict = {'FAIL': (255, 85, 50, 255),
                    'NO DATA': (255, 255, 125, 255),
                    'WARN': (255, 255, 80, 255),
-                   'OK': (125, 255, 125, 255),
+                   'OK': (173, 255, 133, 255),
                    'undefined': (230, 230, 230, 255),
                    'disc': (255, 160, 40, 255),}
     return colors_dict.get(key)
@@ -60,7 +60,7 @@ def get_time_delay_color(dt, dt_thresh):
 
 
 def get_warn_color(count):
-    color = (min([255, 200 + count ** 2]), 255, 80, 255)
+    color = (min([255, 220 + count ** 2]), 255, 80, 255)
     return color