diff --git a/frontend/src/components/ui/date-picker.tsx b/frontend/src/components/ui/date-picker.tsx
index 33dce13..871449b 100644
--- a/frontend/src/components/ui/date-picker.tsx
+++ b/frontend/src/components/ui/date-picker.tsx
@@ -464,7 +464,7 @@ const DatePicker = React.forwardRef<HTMLButtonElement, DatePickerProps>(
               disabled={disabled}
               onMouseDown={(e) => e.preventDefault()}
               onClick={togglePopup}
-              className="absolute right-2.5 top-1/2 -translate-y-1/2 rounded p-0.5 hover:bg-accent/10 transition-colors disabled:opacity-50"
+              className="absolute right-2.5 top-1/2 -translate-y-1/2 rounded p-0.5 bg-background hover:bg-accent/10 transition-colors disabled:opacity-50 z-[1]"
               tabIndex={-1}
               aria-label="Open calendar"
             >
diff --git a/frontend/src/index.css b/frontend/src/index.css
index e819ade..37c9e98 100644
--- a/frontend/src/index.css
+++ b/frontend/src/index.css
@@ -201,9 +201,11 @@ input[type="datetime-local"]::-webkit-calendar-picker-indicator {
 }
 
 /* Hide native picker icon inside DatePicker wrapper (custom icon replaces it) */
+/* Chromium: remove the native calendar icon entirely */
 .datepicker-wrapper input::-webkit-calendar-picker-indicator {
   display: none;
 }
+/* Firefox: opaque background on the custom icon covers the native one (see date-picker.tsx) */
 
 /* ── Form validation — red outline only after submit attempt ── */
 form[data-submitted] input:invalid,