move layout mode to glossary

[estelle]

replaces #38636

this is more a definition than a guide, so moved it to glossary

#218

[github-actions]

Preview URLs (13 pages)

• /en-US/docs/Glossary/Layout_mode
• /en-US/docs/Web/CSS/CSS_Values_and_Units/Value_definition_syntax
• /en-US/docs/Web/CSS/CSS_box_model/Introduction_to_the_CSS_box_model
• /en-US/docs/Web/CSS/CSS_box_model/Mastering_margin_collapsing
• /en-US/docs/Web/CSS/CSS_cascade/actual_value
• /en-US/docs/Web/CSS/CSS_cascade/computed_value
• /en-US/docs/Web/CSS/CSS_cascade/initial_value
• /en-US/docs/Web/CSS/CSS_cascade/specified_value
• /en-US/docs/Web/CSS/CSS_cascade/used_value
• /en-US/docs/Web/CSS/CSS_display/Block_formatting_context
• /en-US/docs/Web/CSS/CSS_display/Containing_block
• /en-US/docs/Web/CSS/CSS_display/Visual_formatting_model
• /en-US/docs/Web/CSS/Reference

Flaws (59)

Note! 12 documents with no flaws that don't need to be listed. 🎉

URL: /en-US/docs/Web/CSS/Reference
Title: CSS reference
Flaw count: 59

• macros:
  • Macro produces link /en-US/docs/Web/CSS/-webkit-line-clamp which is a redirect
  • Can't resolve /en-US/docs/Web/CSS/:active-view-transition
  • Can't resolve /en-US/docs/Web/CSS/:active-view-transition-type()
  • Can't resolve /en-US/docs/Web/CSS/anchor-scope
  • Can't resolve /en-US/docs/Web/CSS/@page/bleed
  • and 54 more flaws omitted

[chrisdavidmills]

LGTM; let's do this.