CSS at-rules demos

[mikehoffms]

Related PRs:

• Update "CSS features reference" MicrosoftDocs/edge-developer#3771

• CSS at-rules demos #135

• Added the following demos, to sync (update) with upstream article CSS Features Reference:

  Dir	Demo name
  /at-rules-font-palette-values/	View @font-palette-values CSS at-rules
  /at-rules-position-try/	View @position-try CSS at-rules
  /at-rules-property/	View @property CSS at-rules
  /at-rules-scope/	View @scope CSS at-rules
  /at-rules-supports/	View @supports CSS at-rules
  /cascade-layers/	Cascade layers
  /focus/	Emulate a focused page
  /highlight-pseudo-elements/	Highlight pseudo-elements

• Readme for repo > Microsoft Edge DevTools

  • Preview: https://github.com/mikehoffms/Demos/blob/user/mikehoffms/css-ref-codepens/README.md#microsoft-edge-devtools
  • Before/live: https://github.com/MicrosoftEdge/Demos/blob/main/README.md#microsoft-edge-devtools
  • Added rows for new demos.
  • Sorted rows in DevTools table by dir, to match GitHub dir order.

AB#62334099

[captainbrosset]

Extra white space between "Open" and "the", maybe in other READMEs too.

Suggested change

	➡️ Open the demo: **[View `@font-palette-values` at-rules](https://microsoftedge.github.io/Demos/at-rules-font-palette-values/)** ⬅️
	➡️ Open the demo: **[View `@font-palette-values` at-rules](https://microsoftedge.github.io/Demos/at-rules-font-palette-values/)** ⬅️

[mikehoffms]

LGTM - Writer/Editor