Minimalistic way to alter base.html.twig in child theme?

I’m working with the Quark theme, which has a grid-size variable in its blueprints. grid-size is applied to header, main content, and footer.

I’d like to make a change so that my header and footer can extend wider (grid-xl) than the main content (grid-md), but the base.html.twig references the same grid-size variable in all three places.

I know I can override the relevant block of the base.html.twig by using a template that extends it in my child theme. But I’m curious if there’s a high-precision method for overriding just this line
<section class="container {{ grid_size }}">
of the body block without copying and editing the whole body block to my child theme template.

The full block in base.html.twig in question is this:

   {% block body %}
        <section id="body-wrapper" class="section">
            <section class="container {{ grid_size }}">
                {% block messages %}
                    {% include 'partials/messages.html.twig' ignore missing %}
                {% endblock %}
                {{ block('content_surround') }}
    {% endblock %}

Any thoughts? Perhaps it’s unnecessary, but I thought a more precise method might make my child theme more update-proof.

That’s really a Twig template design decision, and hopefully theme developers put some consideration into likely customisations. I am pretty sure there’s no elegant/precise way to do this. I have submitted issues to theme and plugin repositories in the past if I think a template change provides a useful common customisation. That might work if you can argue the case.

Ok, thanks for your reply. Hadn’t thought of submitting an issue. But in this case, I don’t think it’s warranted.