Hi,
That
div.product-field.product-field-type-E span.product-fields-title {
display: none;
}
Was exist in the pureMart because most of the people only use "VM - Stockable Variant" plugin. So It doesn't make any sense to show the "custom field title" twice (one title from custom field, and one title from the variant). This was one of the most asked questions.
Anyway, the solution is there, simply remove that display:none; rule and you will be good to go.
Regards.