{%- for main_cat in site.conference.talks.main_categories -%}

{%- for cat in talk.categories -%}
  {%- if cat == main_cat.name -%}
    {%- assign main_cat = main_cat.name -%}
    {%- assign main_cat_color = main_cat.color -%}
    {%- break -%}
  {%- endif -%}
{%- endfor -%}

{%- endfor -%}