diff --git a/src/themes/chartthemebluecerulean_p.h b/src/themes/chartthemebluecerulean_p.h
index 84ba808..dc9fcd1 100644
--- a/src/themes/chartthemebluecerulean_p.h
+++ b/src/themes/chartthemebluecerulean_p.h
@@ -60,7 +60,7 @@ public:
         m_gridLinePen = QPen(QRgb(0x84a2b0));
         m_gridLinePen.setWidth(1);
         m_backgroundShades = BackgroundShadesNone;
-        m_outlinePen = QPen(QRgb(0xd6d6d6));
+        m_outlinePen = QPen(QRgb(0xebebeb));
         m_outlinePen.setWidthF(2.0);
     }
 };
diff --git a/src/themes/chartthemeblueicy_p.h b/src/themes/chartthemeblueicy_p.h
index 9241dfd..e75b4c4 100644
--- a/src/themes/chartthemeblueicy_p.h
+++ b/src/themes/chartthemeblueicy_p.h
@@ -62,7 +62,7 @@ public:
         m_gridLinePen = QPen(QRgb(0xe2e2e2));
         m_gridLinePen.setWidth(1);
         m_backgroundShades = BackgroundShadesNone;
-        m_outlinePen = QPen(QColor(Qt::black));
+        m_outlinePen = QPen(QRgb(0x474747));
         m_outlinePen.setWidthF(2.0);
     }
 };
diff --git a/src/themes/chartthemebluencs_p.h b/src/themes/chartthemebluencs_p.h
index 5c7d733..7dca8e3 100644
--- a/src/themes/chartthemebluencs_p.h
+++ b/src/themes/chartthemebluencs_p.h
@@ -61,7 +61,7 @@ public:
         m_gridLinePen = QPen(QRgb(0xe2e2e2));
         m_gridLinePen.setWidth(1);
         m_backgroundShades = BackgroundShadesNone;
-        m_outlinePen = QPen(QColor(Qt::black));
+        m_outlinePen = QPen(QRgb(0x474747));
         m_outlinePen.setWidthF(2.0);
     }
 };
diff --git a/src/themes/chartthemebrownsand_p.h b/src/themes/chartthemebrownsand_p.h
index 28a156e..0521f6a 100644
--- a/src/themes/chartthemebrownsand_p.h
+++ b/src/themes/chartthemebrownsand_p.h
@@ -61,7 +61,7 @@ public:
         m_gridLinePen = QPen(QRgb(0xd4cec3));
         m_gridLinePen.setWidth(1);
         m_backgroundShades = BackgroundShadesNone;
-        m_outlinePen = QPen(QColor(Qt::black));
+        m_outlinePen = QPen(QRgb(0x222222));
         m_outlinePen.setWidthF(2.0);
     }
 };
diff --git a/src/themes/chartthemedark_p.h b/src/themes/chartthemedark_p.h
index 8aa736a..894f7b0 100644
--- a/src/themes/chartthemedark_p.h
+++ b/src/themes/chartthemedark_p.h
@@ -62,7 +62,7 @@ public:
         m_gridLinePen.setWidth(1);
         m_backgroundShades = BackgroundShadesNone;
         m_outlinePen = QPen(QRgb(0xd6d6d6));
-        m_outlinePen.setWidthF(1.0);
+        m_outlinePen.setWidthF(2.0);
     }
 };
 
diff --git a/src/themes/chartthemehighcontrast_p.h b/src/themes/chartthemehighcontrast_p.h
index f48abcb..dd1f86a 100644
--- a/src/themes/chartthemehighcontrast_p.h
+++ b/src/themes/chartthemehighcontrast_p.h
@@ -64,7 +64,7 @@ public:
         m_backgroundShadesBrush = QBrush(QRgb(0xffeecd));
         m_backgroundShades = BackgroundShadesHorizontal;
         m_outlinePen = QPen(QColor(Qt::black));
-        m_outlinePen.setWidthF(1.0);
+        m_outlinePen.setWidthF(2.0);
     }
 };
 
diff --git a/src/themes/chartthemelight_p.h b/src/themes/chartthemelight_p.h
index 871299f..d270bc1 100644
--- a/src/themes/chartthemelight_p.h
+++ b/src/themes/chartthemelight_p.h
@@ -63,7 +63,7 @@ public:
         m_gridLinePen = QPen(QRgb(0xe2e2e2));
         m_gridLinePen.setWidth(1);
         m_backgroundShades = BackgroundShadesNone;
-        m_outlinePen = QPen(QColor(Qt::black));
+        m_outlinePen = QPen(0x4d4d4d);
         m_outlinePen.setWidthF(2.0);
     }
 };