Help with gallery hover in brine 7.0

Hello, I would love to have some help ! 

I added a hover zoom effect on gallery, it works perfectly but I would like to preserve the block border so the next image of the gallery don't pop out from the border. 

Here is a gif of my website problem : https://share.getcloudapp.com/jku4JwBp

And also I would like to hide the "back button" when it's on the first image. And same for the "next button" when it's on the last image.

https://www.baptistewery.com/ password : 070809baptiste

Here it's my code : 

.sqs-gallery-design-strip {
 
  overflow:visible;
      }

.sqs-gallery-design-strip-slide {
  transition: transform 700ms;
}
.sqs-gallery-design-strip-slide:hover {
transform: scale(1.2);
z-index: 1;
  border:2px solid white;
  border-radius:6px;
}

.sqs-gallery-design-strip img {border-radius:6px;}

.sqs-gallery-design-strip-slide {  
padding-right:0px;  
margin-left:4px;  
margin-top:0px;  
margin-bottom:0px;  

}

Thanks a lot !