Child CSS not used anymore

After upgrading Storefront from 1.5.1 to 1.5.2, my little tweaks in the child theme seem to be ignored. Putting back 1.5.1 reolves the issue. Where to look? I have made the child according to the Codex/Woo doc. My functions.php starts with:

add_action( ‘wp_enqueue_scripts’, ‘theme_enqueue_styles’ );
function theme_enqueue_styles() {
wp_enqueue_style( ‘parent-style’, get_template_directory_uri() . ‘/style.css’ );
}

relevant part of my style.css:

/*
set fixed height, spacing between rows and border
*/
.site-main ul.products li.product {
height: 380px;
margin-bottom: 40px;
border-color: lightgray;
border-style: solid;
border-width: 1px;
}

/*
position the button along the bottom.
Use the same color as the pagination button
*/
.site-main ul.products li.product .button {
margin-bottom: 0;
position: absolute;
top: 340px;
left: 45px;
background-color: #96588a;
}

/*
Give some margin at the top and bottom
*/
.site-main ul.products li.product img {
display: block;
margin: 4px auto 10px;
}

I do want to update to 1.5.2 but do not want to loose the curren look of the site.
TNX
Egbert Jan, NL