diff --git a/containers/libreportal/frontend/components/admin/core/css/admin.css b/containers/libreportal/frontend/components/admin/core/css/admin.css
index 2e338ee..0c53599 100644
--- a/containers/libreportal/frontend/components/admin/core/css/admin.css
+++ b/containers/libreportal/frontend/components/admin/core/css/admin.css
@@ -659,6 +659,11 @@ table.sys-apps tr:hover td { background: rgba(var(--text-rgb), 0.03); }
     pointer-events: none;
 }
 .sys-detail-empty { color: rgba(var(--text-rgb), 0.55); }
+/* The `display: flex` above is an author rule, so it beats the UA
+   `[hidden] { display: none }` — without this the JS `el.hidden = true` can't
+   hide these overlays and they stack on top of a populated graph. */
+.sys-detail-loading[hidden],
+.sys-detail-empty[hidden] { display: none; }
 
 .sys-detail-grid {
     stroke: rgba(var(--text-rgb), 0.07);