Image position on mobile devices

Hello there,

I recently installed a responsive theme for mobile devices visitors of my site.
On small devices like smartphones, I’d like to let the images open with the shadowbox right at the position where they are in the page (at the moment they open on the upper part of the page so visitors need to scroll up to the top to see the opened image).

Maybe a media query in the theme Css would fit? But I could not find the right code (already tried many possibilities like this one :

@media only screen and (max-width: 480px) {
	.sb-player {
	    position: absolute;
	}
}

But nothing could ever do the job till now.
Any idea?
Thanks a lot!

https://ww.wp.xz.cn/plugins/shadowbox-js/