diff --git a/aleksis/apps/chronos/static/css/chronos/timetable.css b/aleksis/apps/chronos/static/css/chronos/timetable.css
index cf1e474d766b78bb0765ef7a03a94faebd89cdfe..bbdbb5b82c664ca908c2cd2088188c0a64395716 100644
--- a/aleksis/apps/chronos/static/css/chronos/timetable.css
+++ b/aleksis/apps/chronos/static/css/chronos/timetable.css
@@ -81,7 +81,7 @@ table.substitutions td, table.substitutions th {
 }
 
 .lesson-with-sub {
-    border: 3px solid #ff0000;
+    border: 3px solid red;
     border-radius: 3px;
 }