diff --git a/containers/libreportal/frontend/components/backup/core/css/backup.css b/containers/libreportal/frontend/components/backup/core/css/backup.css
index fc895c1..1fd5dfa 100755
--- a/containers/libreportal/frontend/components/backup/core/css/backup.css
+++ b/containers/libreportal/frontend/components/backup/core/css/backup.css
@@ -641,6 +641,19 @@
     min-width: 0;
 }
 
+/* The placeholder had no rule at all, so it fell through to the browser
+   default — which on a dark theme renders near-invisible grey against the
+   panel, and "Filter by app, host, or backup id" is the one hint telling you
+   what the box accepts. Written against --text-rgb rather than a fixed grey so
+   it follows the theme: white at 60% on nebula/dark-blue, dark at 60% on light,
+   where a hardcoded #ccc would be unreadable the other way round. Slightly
+   brighter than the task filter's 0.4 because this string is instruction, not
+   decoration. */
+.backup-filter-input::placeholder {
+    color: rgba(var(--text-rgb), 0.6);
+    opacity: 1; /* Firefox dims placeholders by default; the alpha above owns it */
+}
+
 .backup-filter-input:focus,
 .backup-filter-select:focus {
     outline: none;