diff --git a/theme-arc-blue.css b/theme-arc-blue.css
index 303ff62..d0040c7 100644
--- a/theme-arc-blue.css
+++ b/theme-arc-blue.css
@@ -1,3 +1,7 @@
+:root {                                                                                                                                                                
+    --is-dark-theme: true;                                                                                                                                             
+}                                                                                                                                                                      
+
 html {
     background: #171717;
     color: #cacaca;