Add a min-width to the "Automatic dark mode" inputs to stop UI shifting when clicking the "24-hour clock" checkbox. I have no idea where this should go so I just put it somewhere.

ui/scss/component/_form-field.scss

@@ -459,3 +459,8 @@ fieldset-section {
     }
   }
 }
+
+#automatic_dark_mode_range_start,
+#automatic_dark_mode_range_end {
+  min-width: 6em;
+}