_z-index.scss

// Stores a list of z-index values in a central location.  For clarity, when a
// specific value is needed, add a comment explaining why (what other rules the
// value is designed to work with).

$z-layers: (
	".editor-block-list__block-edit::before": 0,
	".editor-block-switcher__arrow": 1,
	".editor-block-list__block .wp-block-more::before": -1,
	".editor-block-list__block {core/image aligned left or right}": 20,
	".editor-block-list__block {core/image aligned wide or fullwide}": 20,
	".freeform-toolbar": 10,
	".editor-block-list__breadcrumb": 100, // drag handler, to be shown below any overlay
	".components-form-toggle__input": 1,
	".editor-inserter__tabs": 1,
	".editor-inserter__tab.is-active": 1,
	".components-panel__header": 1,
	".edit-post-meta-boxes-area.is-loading::before": 1,
	".edit-post-meta-boxes-area .spinner": 5,
	".editor-block-contextual-toolbar": 21,
	".components-popover__close": 5,
	".editor-block-list__insertion-point": 6,
	".editor-inserter-with-shortcuts": 5,
	".editor-warning": 5,
	".block-library-gallery-item__inline-menu": 20,
	".editor-url-input__suggestions": 30,
	".edit-post-header": 30,
	".block-library-button__inline-link .editor-url-input__suggestions": 6, // URL suggestions for button block above sibling inserter
	".wp-block-image__resize-handlers": 1, // Resize handlers above sibling inserter

	// Side UI active buttons
	".editor-block-settings-remove": 1,
	".editor-block-mover__control": 1,

	// Active pill button
	".components-button.is-button {:focus or .is-primary}": 1,

	// The drag image should show up above the entire UI
	".components-draggable__clone": 1000000000,

	// Should have higher index than the inset/underlay used for dragging
	".components-placeholder__fieldset": 1,
	".editor-block-list__block-edit .reusable-block-edit-panel *": 1,

	// Show drop zone above most standard content, but below any overlays
	".components-drop-zone": 100,
	".components-drop-zone__content": 110,

	// Block controls, particularly in nested contexts, floats aside block and
	// should overlap most block content.
	".editor-block-list__block.is-{selected,hovered} .editor-block-{settings-menu,mover}": 80,

	// Small screen inner blocks overlay must be displayed above drop zone,
	// settings menu, and movers.
	".editor-inner-blocks__small-screen-overlay:after": 120,

	// Show sidebar above wp-admin navigation bar for mobile viewports:
	// #wpadminbar { z-index: 99999 }
	".edit-post-sidebar": 100000,
	".edit-post-layout .edit-post-post-publish-panel": 100001,

	// Show sidebar in greater than small viewports above editor related elements
	// but bellow #adminmenuback { z-index: 100 }
	".edit-post-sidebar {greater than small}": 90,

	// Show notices below expanded wp-admin submenus:
	// #adminmenuwrap { z-index: 9990 }
	".components-notice-list": 9989,

	// Show modal under the wp-admin menus and the popover
	".components-modal__screen-overlay": 100000,

	// Show popovers above wp-admin menus and submenus and sidebar:
	// #adminmenuwrap { z-index: 9990 }
	".components-popover": 1000000,

	// Shows adminbar quicklink submenu above bottom popover:
	// #wpadminbar ul li {z-index: 99999;}
	".components-popover.is-bottom": 99990,

	".components-autocomplete__results": 1000000,

	".skip-to-selected-block": 100000,
	".edit-post-toggle-publish-panel": 100000,

	// Show NUX tips above popovers, wp-admin menus, submenus, and sidebar:
	".nux-dot-tip": 1000001,

	// Show tooltips above NUX tips, wp-admin menus, submenus, and sidebar:
	".components-tooltip": 1000002
);

@function z-index( $key ) {
	@if map-has-key( $z-layers, $key ) {
		@return map-get( $z-layers, $key );
	}

	@error "Error: Specified z-index `#{$key}` does not exist in the mapping";
}