Revert "fix: scope global sidebar styles to the app"

This reverts commit 2460c53.

Signed-off-by: Anna Larch <anna@nextcloud.com>

css/app-sidebar.scss

@@ -3,7 +3,7 @@
  * SPDX-License-Identifier: AGPL-3.0-or-later
  */
 
-.app-calendar .app-sidebar,
+.app-sidebar,
 .event-popover .event-popover__inner {
 	.editor-invitee-list-empty-message,
 	.editor-reminders-list-empty-message,