diff --git a/packages/mermaid/src/diagrams/class/styles.js b/packages/mermaid/src/diagrams/class/styles.js
index 9d0803335..f12f609f9 100644
--- a/packages/mermaid/src/diagrams/class/styles.js
+++ b/packages/mermaid/src/diagrams/class/styles.js
@@ -121,13 +121,13 @@ g.classGroup line {
 }
 
 #aggregationStart, .aggregation {
-  fill: ${options.mainBkg} !important;
+  fill: transparent !important;
   stroke: ${options.lineColor} !important;
   stroke-width: 1;
 }
 
 #aggregationEnd, .aggregation {
-  fill: ${options.mainBkg} !important;
+  fill: transparent !important;
   stroke: ${options.lineColor} !important;
   stroke-width: 1;
 }