Gallery Autoplay with slower fade

Hi

The transition between the images is too fast for me, I would like to slow it down. I found this code in the forum, it almost works, but unfortunately the previous image is faded out and only then the new one is displayed. I would like to merge it.

.slide {
 -webkit-transition: opacity 6000ms ease-in-out !important;
  -moz-transition: opacity 6000ms ease-in-out !important;
  -o-transition: opacity 6000ms ease-in-out !important;
   transition: opacity 6000ms ease-in-out !important;
}

Site: https://aquila.squarespace.com/therapie
PW: aquila

Thanks for help!
Best,
Fabian