Seven theme's details/summary doesn't have a hover style

avpaderno → credited bnjmnm → .

It seems this has been already implemented, since contains the css/base/elements.css file following styles.

/**
 * Unfortunately, text-decoration for details summary is not supported on all
 * browsers. So we add a span (which can handle text-decoration) in Seven's
 * templates/details.html.twig. In case there are other details templates that
 * don't have the span, we provide text-decoration in the parent selector.
 * This provides maximum compatibility and coverage with minimal disruption.
 */
details summary:not(.seven-details__summary):focus {
  text-decoration: underline;
}

details summary:focus span {
  text-decoration: underline;
}

Those lines have been added as part of the initial commit.

I took this screenshot from the /admin/modules page. Are there other pages which could be used to check?