Add note about issues with popover default styles

[jakearchibald]

Description

The popover element has default styles that get in the way of expected usage of anchor positioning. I've added notes to various docs to help developers avoid these gotchas.

[github-actions]

Preview URLs

• /en-US/docs/Web/API/Popover_API/Using
• /en-US/docs/Web/CSS/anchor
• /en-US/docs/Web/CSS/position-area

Flaws (1)

Note! 2 documents with no flaws that don't need to be listed. 🎉

URL: /en-US/docs/Web/CSS/position-area
Title: position-area
Flaw count: 1

• unknown:
  • Error parsing /shared-assets/images/diagrams/css/anchor-positioning/position-area.svg: No such file or directory (os error 2)

External URLs (6)

URL: /en-US/docs/Web/API/Popover_API/Using
Title: Using the Popover API

• https://github.com/w3c/csswg-drafts/issues/10258 (1 time) (Note! This may be a new URL 👀)
• https://html.spec.whatwg.org/multipage/rendering.html (1 time) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Web/CSS/anchor
Title: anchor()

• https://github.com/w3c/csswg-drafts/issues/10258 (1 time) (Note! This may be a new URL 👀)
• https://html.spec.whatwg.org/multipage/rendering.html (1 time) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Web/CSS/position-area
Title: position-area

• https://github.com/w3c/csswg-drafts/issues/10258 (1 time) (Note! This may be a new URL 👀)
• https://html.spec.whatwg.org/multipage/rendering.html (1 time) (Note! This may be a new URL 👀)

(comment last updated: 2025-08-14 09:49:49)

[pepelsbey]

Looks good to me. Thank you!