Update boingy-graph.html
<!-- FILTER OVERLAY -->
-<div style="position: absolute; top: 42px; left: 32px; opacity: 0.9;"
+<div style="position: absolute; top: 42px; left: 32px; opacity: 0.9; z-index: 1000;"
ng-show="$ctrl.showFilters"> <!-- using `show` so filters do not reset when reopening -->
<waltz-sub-section name="Filters">
<content>
