diff --git a/customize.dist/src/less2/include/colortheme-dark.less b/customize.dist/src/less2/include/colortheme-dark.less
index fc17d7d24..c2312b236 100644
--- a/customize.dist/src/less2/include/colortheme-dark.less
+++ b/customize.dist/src/less2/include/colortheme-dark.less
@@ -414,3 +414,7 @@
 @cp_whiteboard-board-border: @cryptpad_color_grey_800;
 @cp_whiteboard-bg: @cp_app-bg;
 @cp_whiteboard-fg: @cryptpad_text_col;
+
+// Flatpickr
+@cp_flatpickr-bg: @cp_app-bg;
+
diff --git a/customize.dist/src/less2/include/colortheme.less b/customize.dist/src/less2/include/colortheme.less
index f353758c8..24f3f037f 100644
--- a/customize.dist/src/less2/include/colortheme.less
+++ b/customize.dist/src/less2/include/colortheme.less
@@ -414,3 +414,6 @@
 @cp_whiteboard-board-border: @cryptpad_color_grey_600;
 @cp_whiteboard-bg: @cp_app-bg;
 @cp_whiteboard-fg: @cryptpad_text_col;
+
+// Flatpickr
+@cp_flatpickr-bg:  @cp_app-bg;
diff --git a/customize.dist/src/less2/include/forms.less b/customize.dist/src/less2/include/forms.less
index 7a2b90e42..8aa1b2e6d 100644
--- a/customize.dist/src/less2/include/forms.less
+++ b/customize.dist/src/less2/include/forms.less
@@ -279,4 +279,11 @@
             color: @cp_drive-infobox-fg;
         }
     }
+
+    // Flatpickr
+    body {
+        .flatpickr-calendar {
+            background: @cp_flatpickr-bg;
+        }
+    }
 }