Adjusting Gallery Lightbox-Text Position

Site URL: https://endive-gold-pzxj.squarespace.com/config/

Hi, 

I'm having some difficulty adjusting the position of the Gallery Lightbox-Text on the Mobile version of my site.
The Lightbox captions are currently cut off at the bottom of the page, see attached image.

I think that this section of code is causing the problem:
Location: Design> Custom CSS

 /* gallery caption */
.style-gallery-lightbox-text {
    top: unset !important;
}
}

I'm trying to have the caption visible at the bottom of the page, across all mobile devices. 

On my website there is also have another section of code which relates to the Lightbox Text. I've included it below as it also might be relevant to my question.
Location: Settings> Advanced> Code Injection> Header

<style>
  figcaption.gallery-caption.gallery-caption-grid-simple {
    display: none;
}
  .style-gallery-lightbox-text {
		position: absolute;
        top: 70%;
        left: 50%;
        margin-right: -50%;
        transform: translate(-50%, -50%) }
    font-size: .3em
    text-align: center;
}
}
}
</style>

Website Link: https://endive-gold-pzxj.squarespace.com/config/
Password: 123

Any help you could offer would be greatly appreciated!

Kind Regards,
Dom