hi, im trying to change the thumbnail image for the "empty cave slot" element in my den, but i've no idea where to put the image link so it will be in the correct place. for the images for each of my occupied caves and pregnant/unsorted/overview i use

a[href$="CAVEID"]>div.cave-grid>img {
content: url('imageurlhere') !important
}

but since the empty cave doesnt have an id or page to go to i dont know what to put in that "CAVEID" part above where i've put it for everything else. if i put it as "create-cave.php" the image changes successfully but only on my end from my own account, you cant see it from another profile. anyone know what i can do?

right now the image defaults to the same one as my pregnant lioness' den if thats important.