https://alistapart.com/article/motion-with-meaning-semantic-animation-in-interface-design/

We should probably use prefers-reduced-motion to set --animation-quick and --animation-slow to 0?

Good examples in Nextcloud

• Hover/focus of the main app navigation [Bug]: Increased space between apps and name when hovering the apps menu #46542 (comment)
• Talk: Device/background picker fix(MediaSettings): jumping on devices/backgrounds switch spreed#12815
• Talk: Sending messages → Sliding them from the input field into the content
• Modals open with a slight zoom-in animation
• Opening of left navigation and right sidebar
• …

Where we can do more

• Action menus → Quick shift-down animation
• Switching tabs in the sidebar → Movement of highlight bar
• Files: Expanding of "Favorites" and "Shares" in left navigation → Expand/collapse animation
• Talk, Mail and other lists: Deleting items → Quick vertical compression animation
• Mail: "Show all mailboxes" and "Collapse mailboxes" → Expand/collapse animation
• …