Hey Andre,
The css would work only once upon loading. As soon as you resize, or change the font size, it will not have the same height again. Please remove the custom css and use this JS code instead. Please edit the page back in Cornerstone and find the Cornerstone custom js section, Custom JS and insert the following custom js code
jQuery( function($) {
function card_resize() {
var card_timeout = setTimeout ( function() {
clearTimeout ( card_timeout );
$('.x-card-outer .x-card-inner').each(function(index, element){
var h = $(this).width();
$(this).css('height',h);
} );
}, 300 ); //let's add a 300ms delay
}
$(document).ready( card_resize );
$(window).resize( card_resize );
$(window).load( card_resize );
} );
Hope this helps. Please let us know how it goes.