diff --git a/app/assets/javascripts/app/views/generic/datetime.jst.eco b/app/assets/javascripts/app/views/generic/datetime.jst.eco
index 2f62c75a7..c4678611d 100644
--- a/app/assets/javascripts/app/views/generic/datetime.jst.eco
+++ b/app/assets/javascripts/app/views/generic/datetime.jst.eco
@@ -1,6 +1,6 @@
-<div class="controls--bundle" data-name="<%= @attribute.nameRaw %>">
+<div class="horizontal" data-name="<%= @attribute.nameRaw %>">
   <input type="hidden" value="<%= @attribute.value %>" name="<%= @attribute.name %>">
-  <input type="text" value="" class="form-control js-datepicker" data-item="date">
+  <input type="text" value="" class="form-control flex-shrink-horizontal js-datepicker" data-item="date">
   <div class="controls-label"><%- @T('at') %></div>
   <input type="text" value="" class="form-control time js-timepicker" data-item="time">
 </div>
\ No newline at end of file
diff --git a/app/assets/stylesheets/zammad.scss b/app/assets/stylesheets/zammad.scss
index 83c61b8ee..49e30e783 100644
--- a/app/assets/stylesheets/zammad.scss
+++ b/app/assets/stylesheets/zammad.scss
@@ -1193,13 +1193,9 @@ fieldset > .form-group {
   margin-bottom: 0;
 }
 
-.controls--bundle {
-  display: flex;
-
-  .controls-label {
-    margin: 11px 10px 0;
-    flex-shrink: 0;
-  }
+.controls-label {
+  margin: 11px 10px 0;
+  flex-shrink: 0;
 }
 
 input[type="radio"], 
@@ -6977,6 +6973,21 @@ body.fit {
   flex: 1;
 }
 
+/*
+
+  Firefox minimum content bugfix
+  
+  https://github.com/philipwalton/flexbugs#1-minimum-content-sizing-of-flex-items-not-honored
+
+  "By default, flex items won’t shrink below their minimum 
+  content size (the length of the longest word or fixed-size element). 
+  To change this, set the min-width or min-height property."
+  
+*/
+.flex-shrink-horizontal {
+  min-width: 0;
+}
+
 .flex-full {
   flex: 1 1 100%;
 }