Replace Index slideshow gallery images for mobile

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Hi Guys,

I wanted to know if its possible to replace the Index slideshow gallery images for mobile? I have tried this code for to get it show the full image as it was cutting my image off.

<style>
  @media screen and (max-width:640px) {
  .Index-gallery-item-image img {
    width: 100% !important;
    left: 0 !important;
    top: 0 !important;
    height: auto !important;
}
  }
</style>

But using this code shows the full image, but doesn't show my button that I have on-top of the index slideshow correctly. So now I've created different images for mobile, Is there a way I can just add these images to show on mobile? I have 3 images in my slideshow. 

<style>
  @media screen and (max-width:640px) {
  .Index-gallery-item-image img {
    width: 100% !important;
    left: 0 !important;
    top: 0 !important;
    height: auto !important;
}
    .Index-gallery-wrapper.gallery-root {
    position: relative;
}
.Index-gallery-item-content {
    max-width: 100% !important;
    padding-top: 0 !important;
    position: static;
}
    .Index-gallery-item-content-body a {
    position: absolute;
    top: 5%;
    left: 50%;
    transform: translateX(-50%);
}
  }
</style>