3 minutes ago, matusrajnoha said:I created a child theme. Therefore my file product-cover-thumbnails.tpl is under child_classics ...
Therefore, I am not worried about editing files. Child-themes only override default files.
I don't think you need to upgrade.overwrite is removed:
<div class="layer hidden-sm-down" data-toggle="modal" data-target="#product-modal">
.product-cover .layer:hover {opacity: 0;} is here:
themes/classic/assets/css/custom.css
.product-cover .layer:hover {opacity: 0;}
I can turn off child-themes at any time and the rest is still in its original state.