Update in/active states for flag and stop

src/components/green-flag/green-flag.css

 .green-flag {
     width: 16px;
     height: 16px;
+    opacity: 0.5;
 }
-.green-flag.is-active {
-    filter: saturate(200%) brightness(150%);
+.green-flag.is-active,
+.green-flag:hover {
+    opacity: 1;
 }

src/components/stop-all/stop-all.css

 .stop-all {
     width: 16px;
     height: 16px;
+    opacity: 0.5;
 }
-.stop-all.is-active {
-    filter: saturate(200%) brightness(150%);
+.stop-all.is-active,
+.stop-all:hover {
+    opacity: 1;
 }