The caret on details elements is invisible on hover and expansion in forced color mode

Problem/Motivation

In forced color mode the caret on any details element/fieldset is disappearing on hover or when the detail element is expanded. The caret is only visible when the details element is collapsed.

Steps to reproduce

• Enable forced color mode in for example the microsoft edge devtools. on the rendering tab chose prefers-color-scheme: dark, forced-colors: active, and prefers-contrast:more
• Go to for example admin/config/people/accounts and hover or expand any of the fieldsets

Proposed resolution

Ensure that the caret is visible all the time

Remaining tasks

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet