lours.net/user/themes/le_style_de_lours/templates/partials/logo.html.twig

{% set logo = theme_var(mobile ? 'custom_logo_mobile' : 'custom_logo') %}
{% if logo %}
  {% set logo_file = (logo|first).name %}

  <img src="{{ url('theme://images/logo/' ~ logo_file)  }}" alt="{{ site.name }}" />

{% else %}
  {% include('@images/grav-logo.svg') %}
{% endif %}