feat: Add content for overlay and discrete animation features

[chrisdavidmills]

Note: This technical review is now completed and approved. For the follow-on editorial review, see #29943.

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Description

This PR adds content for multiple related features that go together to enable the creation of exit/entrance animations using simple CSS, or to put it another way, animating to/from display: none (this includes top layer elements like popovers), or animating elements when they have just been added to the DOM.

Specifically, these are:

• @starting-style: Chrome 117
• The overlay property: Chrome 117
• Animating to/from display: none and content-visibility: hidden: Chrome 116
• The transition-behavior property: Chrome 117

See my research document for more details of what this project aims to add.

Motivation

Additional details

Related issues and pull requests

[github-actions]

Preview URLs (12 pages)

• /en-US/docs/Web/API/CSSStartingStyleRule
• /en-US/docs/Web/API/Popover_API/Using
• /en-US/docs/Web/CSS/@starting-style
• /en-US/docs/Web/CSS/CSS_animations/Using_CSS_animations
• /en-US/docs/Web/CSS/CSS_transitions/Using_CSS_transitions
• /en-US/docs/Web/CSS/content-visibility
• /en-US/docs/Web/CSS/display
• /en-US/docs/Web/CSS/overlay
• /en-US/docs/Web/CSS/transition-behavior
• /en-US/docs/Web/CSS/transition-property
• /en-US/docs/Web/CSS/transition
• /en-US/docs/Web/HTML/Element/dialog

Flaws (2)

Note! 11 documents with no flaws that don't need to be listed. 🎉

URL: /en-US/docs/Web/CSS/@starting-style
Title: @starting-style
Flaw count: 2

• broken_links:
  • No need for the pathname in anchor links if it's the same page
  • Link points to the page it's already on

External URLs (3)

URL: /en-US/docs/Web/CSS/transition-behavior
Title: transition-behavior

• https://developer.chrome.com/blog/entry-exit-animations/ (1 time) (Note! This may be a new URL 👀)

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URL: /en-US/docs/Web/CSS/overlay
Title: overlay

• https://developer.chrome.com/blog/entry-exit-animations/ (2 times) (Note! This may be a new URL 👀)

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URL: /en-US/docs/Web/CSS/@starting-style
Title: @starting-style

• https://developer.chrome.com/blog/entry-exit-animations/ (1 time) (Note! This may be a new URL 👀)

(comment last updated: 2023-10-31 17:01:36)

[github-actions]

This pull request has merge conflicts that must be resolved before it can be merged.

[chrisdavidmills]

This PR has been dormant for a while, but it has been reviewed (thanks @josepharhar!), and the content looks good. I am going to call the technical review completed. The next stage is to close this PR and open a new editorial review PR based on the same branch, which I'll pass to one of the MDN editorial team for final review before publication.

[chrisdavidmills]

Something I noticed. I'll fix it when I look at this again tomorrow.