Quark: different hero-images for different screen-sizes

I installed a Quark One-Page Site Skeleton, Maybe this will be our new band website.
In order for the band to be fully represented on the Hero image on both large, horizontally oriented displays and small, vertically oriented displays, a separate image would have to be inserted for small screens.

I’ve tried in CSS with the @media tag, but have failed so far. I don’t see which class the background-image belongs to.

Maybe someone can find a solution?

I have found the following solution which is sufficient for my needs. Surely it could be done more elegantly.

  1. templates/partials/hero.html.twig
    Delete in line 1:
    {% if hero_image %}style=“background-image: url(‘{{ hero_image.url }}’);”{% endif %}
  2. css/custom.css
    section.section.hero {
    background-image: url(‘/0eg/user/pages/01.home/01._hero/eghorizontal.jpg’);
    @media (max-width: 840px) {
    section.section.hero {
    background-image: url(“/0eg/user/pages/01.home/01._hero/egvertical.jpg”);

I still need to get closer to the optimal breakpoint.