diff --git a/docs/config/theming.md b/docs/config/theming.md
index 63271a39b7..8ab1eaf1d8 100644
--- a/docs/config/theming.md
+++ b/docs/config/theming.md
@@ -250,7 +250,7 @@ The theming engine will only recognize hex colors and not color names. So, the v
 | actorBkg              | mainBkg                        | Actor Background Color      |
 | actorBorder           | primaryBorderColor             | Actor Border Color          |
 | actorTextColor        | primaryTextColor               | Actor Text Color            |
-| actorLineColor        | grey                           | Actor Line Color            |
+| actorLineColor        | actorBorder                    | Actor Line Color            |
 | signalColor           | textColor                      | Signal Color                |
 | signalTextColor       | textColor                      | Signal Text Color           |
 | labelBoxBkgColor      | actorBkg                       | Label Box Background Color  |
diff --git a/packages/mermaid/src/docs/config/theming.md b/packages/mermaid/src/docs/config/theming.md
index 0e08532837..0f489db2a7 100644
--- a/packages/mermaid/src/docs/config/theming.md
+++ b/packages/mermaid/src/docs/config/theming.md
@@ -172,7 +172,7 @@ The theming engine will only recognize hex colors and not color names. So, the v
 | actorBkg              | mainBkg                        | Actor Background Color      |
 | actorBorder           | primaryBorderColor             | Actor Border Color          |
 | actorTextColor        | primaryTextColor               | Actor Text Color            |
-| actorLineColor        | grey                           | Actor Line Color            |
+| actorLineColor        | actorBorder                    | Actor Line Color            |
 | signalColor           | textColor                      | Signal Color                |
 | signalTextColor       | textColor                      | Signal Text Color           |
 | labelBoxBkgColor      | actorBkg                       | Label Box Background Color  |
diff --git a/packages/mermaid/src/themes/theme-base.js b/packages/mermaid/src/themes/theme-base.js
index d1a6eae2ab..dde3b9ecff 100644
--- a/packages/mermaid/src/themes/theme-base.js
+++ b/packages/mermaid/src/themes/theme-base.js
@@ -70,7 +70,7 @@ class Theme {
     this.actorBorder = this.actorBorder || this.primaryBorderColor;
     this.actorBkg = this.actorBkg || this.mainBkg;
     this.actorTextColor = this.actorTextColor || this.primaryTextColor;
-    this.actorLineColor = this.actorLineColor || 'grey';
+    this.actorLineColor = this.actorLineColor || this.actorBorder;
     this.labelBoxBkgColor = this.labelBoxBkgColor || this.actorBkg;
     this.signalColor = this.signalColor || this.textColor;
     this.signalTextColor = this.signalTextColor || this.textColor;
diff --git a/packages/mermaid/src/themes/theme-dark.js b/packages/mermaid/src/themes/theme-dark.js
index c566251090..ae264e9e93 100644
--- a/packages/mermaid/src/themes/theme-dark.js
+++ b/packages/mermaid/src/themes/theme-dark.js
@@ -109,7 +109,7 @@ class Theme {
     this.actorBorder = this.border1;
     this.actorBkg = this.mainBkg;
     this.actorTextColor = this.mainContrastColor;
-    this.actorLineColor = this.mainContrastColor;
+    this.actorLineColor = this.actorBorder;
     this.signalColor = this.mainContrastColor;
     this.signalTextColor = this.mainContrastColor;
     this.labelBoxBkgColor = this.actorBkg;
diff --git a/packages/mermaid/src/themes/theme-default.js b/packages/mermaid/src/themes/theme-default.js
index 6aa18fcc78..c149b43f34 100644
--- a/packages/mermaid/src/themes/theme-default.js
+++ b/packages/mermaid/src/themes/theme-default.js
@@ -53,7 +53,7 @@ class Theme {
     this.actorBorder = 'calculated';
     this.actorBkg = 'calculated';
     this.actorTextColor = 'black';
-    this.actorLineColor = 'grey';
+    this.actorLineColor = 'calculated';
     this.signalColor = 'calculated';
     this.signalTextColor = 'calculated';
     this.labelBoxBkgColor = 'calculated';
diff --git a/packages/mermaid/src/themes/theme-forest.js b/packages/mermaid/src/themes/theme-forest.js
index 0270f51ff9..8ebe78ec89 100644
--- a/packages/mermaid/src/themes/theme-forest.js
+++ b/packages/mermaid/src/themes/theme-forest.js
@@ -46,7 +46,7 @@ class Theme {
     this.actorBorder = 'calculated';
     this.actorBkg = 'calculated';
     this.actorTextColor = 'black';
-    this.actorLineColor = 'grey';
+    this.actorLineColor = 'calculated';
     this.signalColor = '#333';
     this.signalTextColor = '#333';
     this.labelBoxBkgColor = 'calculated';
diff --git a/packages/mermaid/src/themes/theme-neutral.js b/packages/mermaid/src/themes/theme-neutral.js
index 446a9189d4..032ed43c6a 100644
--- a/packages/mermaid/src/themes/theme-neutral.js
+++ b/packages/mermaid/src/themes/theme-neutral.js
@@ -58,7 +58,7 @@ class Theme {
     this.actorBorder = 'calculated';
     this.actorBkg = 'calculated';
     this.actorTextColor = 'calculated';
-    this.actorLineColor = 'calculated';
+    this.actorLineColor = this.actorBorder;
     this.signalColor = 'calculated';
     this.signalTextColor = 'calculated';
     this.labelBoxBkgColor = 'calculated';