I'm using a theme that use background image in template like this:
{% if page.header.background_image != '' %}
{% set background_html = 'style="background-image: url(' ~ page.media.images[page.header.background_image].url ~ ');"' %}
{% else %}
{% set background_html = "" %}
{% endif %}
In other page templates (in admin) I can see upload field, but not in modular - I see only title and order of modules.
I want to take advantage of image upload, but I can find place to put them, nor add it in the modular.yaml in the theme (I don't want to edit modular from the grav installation).
My goal is to edit theme in the manner where I can use the image upload.