diff --git a/internal/server/web/static/app.css b/internal/server/web/static/app.css
index 278b052..73ff463 100644
--- a/internal/server/web/static/app.css
+++ b/internal/server/web/static/app.css
@@ -10,6 +10,8 @@
   --ok: #37c871;
 }
 * { box-sizing: border-box; }
+/* The hidden attribute wins over any display set by a class. */
+[hidden] { display: none !important; }
 body {
   margin: 0;
   background: var(--bg);