diff --git a/theme/boost/scss/moodle/course.scss b/theme/boost/scss/moodle/course.scss
index 7662edcca9f..4a13d629809 100644
--- a/theme/boost/scss/moodle/course.scss
+++ b/theme/boost/scss/moodle/course.scss
@@ -89,6 +89,12 @@
                 text-indent: -31px;
                 padding-left: 31px;
             }
+
+            .dimmed {
+                .activityicon {
+                    opacity: .5;
+                }
+            }
         }
     }