[Bug]: Deck-Karten im dunklen Design - Kartenumrandung nicht erkennbar

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github OR Nextcloud Community Forum (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

Steps to reproduce

1. Login - Benutzer-Icon oben rechts - Menüpunkt "Aussehen und Barrierefreiheit"
2. Design umstellen auf "Dunkles Design"
3. Die App "Deck" aufrufen
4. => Aufgabenkacheln nicht nicht erkennbar, weil die Rahmenfarbe dem Hintergrund zu stark ähnelt. Zum Vergleich im Screenshot zu siehen: Die Rahmenfarbe der Felder in der Sidebar auf der rechten Seite sind gut zu erkennen.

Expected behavior

Die Rahmenfarbe sollte so gewählt werden, dass sich die Aufgabenkacheln von der Hintergrundebene erkennbar abheben.

Installation method

None

Nextcloud Server version

28

Operating system

None

PHP engine version

None

Web server

None

Database engine version

None

Is this bug present after an update or on a fresh install?

None

Are you using the Nextcloud Server Encryption module?

None

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

No response

List of activated Apps

No response

Nextcloud Signing status

No response

Nextcloud Logs

No response

Additional info

No response

Start by reproducing the issue in the Deck app with Nextcloud's dark theme enabled, following the listed navigation steps, and compare the task-card borders with the sidebar fields shown in the screenshot. Done means the task cards are visibly distinct from their background while preserving the dark theme appearance.