diff --git a/assets/js/chart.js b/assets/js/chart.js
index 4d76e7f6..ccf950d4 100644
--- a/assets/js/chart.js
+++ b/assets/js/chart.js
@@ -1,5 +1,5 @@
 function css(name) {
-  return getComputedStyle(document.documentElement).getPropertyValue(name);
+  return "rgb(" + getComputedStyle(document.documentElement).getPropertyValue(name) + ")";
 }
 
 Chart.defaults.font.size = 14;
diff --git a/assets/js/mermaid.js b/assets/js/mermaid.js
index 59b3e1a1..94795fe4 100644
--- a/assets/js/mermaid.js
+++ b/assets/js/mermaid.js
@@ -1,5 +1,5 @@
 function css(name) {
-  return getComputedStyle(document.documentElement).getPropertyValue(name);
+  return "rgb(" + getComputedStyle(document.documentElement).getPropertyValue(name) + ")";
 }
 
 mermaid.initialize({