{%- comment -%}1日は86400秒{%- endcomment -%}
{%- assign days = 14 | times: 86400 -%}
{%- assign two_weeks_after_publish = product.published_at| date: "%s" | plus: days | date: "%Y-%m-%d" -%}
{%- if two_weeks_after_publish > now -%}
<span>NEW</span>
{%- endif -%}