diff --git a/data/theme/gtk-styles.css b/data/theme/gtk-styles.css
index 98be14e1..45f23a3d 100644
--- a/data/theme/gtk-styles.css
+++ b/data/theme/gtk-styles.css
@@ -424,7 +424,7 @@ weekgrid.now-strip {
 
 weekgrid:selected,
 .week-header:selected {
-    background-color: alpha(@theme_selected_bg_color, 0.4);
+    background-color: alpha(@theme_selected_bg_color, 0.25);
 }
 
 .week-header:selected {