eventlineup enhancments (availability notes, reminders, flags popup)

src/scss/application.scss

@@ -363,3 +363,7 @@ div[id^="event-lineup"] .Panel {
 .scroll-horizontal {
   overflow-x: scroll;
 }
+
+button:has(+.position-label-flags :checked) {
+  @extend .Button--blue
+}