TMSS-2886: keep header in sight

SAS/TMSS/backend/src/tmss/tmssapp/views.py

@@ -787,6 +787,8 @@ def public_schedule(request):
           background-color: #AAAAAA;
           font-weight: bold; 
           text-align: left; 
+          position: sticky;
+          top: 0px;
         }
         tr:nth-child(even) {
           background-color: #EEEEEE;