Hello,
This custom CSS was added in Theme Options > Theme Custom CSS > Global custom CSS for the mentioned version:
.single-product .main-images > div {
border: 2px solid #e2e2e2 !important;
border-radius: 20px;
padding: 5px;
margin-bottom: 35px;
}
.single-product .main-images > div:hover {
border-color: #5556ff !important;
}
Regards