Slow down transitions in gallery slideshow

Site URL: https://seadragon-pear-6ndb.squarespace.com/

password: op1

I'd like to slow down the fade transition -- and keep the text and photo transitioning at the same rate -- in my slideshow gallery on my home page. I have tried the following code and a few other variations, but all of the options I'm finding from past forum discussions are causing the text to fade in more quickly than the photo. Any ideas? 

.slide {
   visibility: visible !important;
   -webkit-transition: opacity 3s ease-in-out;
   -moz-transition: opacity 3s ease-in-out;
   -o-transition: opacity 3s ease-in-out;
   transition: opacity 3s ease-in-out;
}