Set top toolbar size dynamically

packages/block-editor/src/components/block-toolbar/style.scss

@@ -252,6 +252,16 @@
 		flex-shrink: 1;
 	}
 
+	@include break-medium() {
+		.block-editor-block-contextual-toolbar.is-fixed {
+			.components-toolbar,
+			.components-toolbar-group {
+				flex-shrink: 0;
+			}
+		}
+	}
+
+
 	.block-editor-rich-text__inline-format-toolbar-group {
 		.components-button + .components-button {
 			margin-left: 6px;

packages/block-editor/src/components/block-tools/block-contextual-toolbar.js

@@ -7,7 +7,12 @@ import classnames from 'classnames';
  * WordPress dependencies
  */
 import { __ } from '@wordpress/i18n';
-import { useEffect, useRef, useState } from '@wordpress/element';
+import {
+	useLayoutEffect,
+	useEffect,
+	useRef,
+	useState,
+} from '@wordpress/element';
 import { hasBlockSupport, store as blocksStore } from '@wordpress/blocks';
 import { useSelect } from '@wordpress/data';
 import {
@@ -77,6 +82,77 @@ function BlockContextualToolbar( { focusOnMount, isFixed, ...props } ) {
 		setIsCollapsed( false );
 	}, [ selectedBlockClientId ] );
 
+	const isLargerThanTabletViewport = useViewportMatch( 'large', '>=' );
+	const isFullscreen =
+		document.body.classList.contains( 'is-fullscreen-mode' );
+
+	useLayoutEffect( () => {
+		// don't do anything if not fixed toolbar
+		if ( ! isFixed || ! blockType ) {
+			return;
+		}
+
+		const blockToolbar = document.querySelector(
+			'.block-editor-block-contextual-toolbar'
+		);
+
+		if ( ! blockToolbar ) {
+			return;
+		}
+
+		if ( ! isLargerThanTabletViewport ) {
+			// set the width of the toolbar to auto
+			blockToolbar.style = {};
+			return;
+		}
+
+		if ( isCollapsed ) {
+			// set the width of the toolbar to auto
+			blockToolbar.style.width = 'auto';
+			return;
+		}
+
+		// get the width of the pinned items in the post editor
+		const pinnedItems = document.querySelector(
+			'.edit-post-header__settings'
+		);
+
+		// get the width of the left header in the site editor
+		const leftHeader = document.querySelector(
+			'.edit-site-header-edit-mode__end'
+		);
+
+		const computedToolbarStyle = window.getComputedStyle( blockToolbar );
+		const computedPinnedItemsStyle = pinnedItems
+			? window.getComputedStyle( pinnedItems )
+			: false;
+		const computedLeftHeaderStyle = leftHeader
+			? window.getComputedStyle( leftHeader )
+			: false;
+
+		const marginLeft = parseFloat( computedToolbarStyle.marginLeft );
+		const pinnedItemsWidth = computedPinnedItemsStyle
+			? parseFloat( computedPinnedItemsStyle.width ) + 10 // 10 is the pinned items padding
+			: 0;
+		const leftHeaderWidth = computedLeftHeaderStyle
+			? parseFloat( computedLeftHeaderStyle.width )
+			: 0;
+
+		// set the new witdth of the toolbar
+		blockToolbar.style.width = `calc(100% - ${
+			leftHeaderWidth +
+			pinnedItemsWidth +
+			marginLeft +
+			( isFullscreen ? 0 : 160 ) // the width of the admin sidebar expanded
+		}px)`;
+	}, [
+		isFixed,
+		isLargerThanTabletViewport,
+		isCollapsed,
+		isFullscreen,
+		blockType,
+	] );
+
 	const isToolbarEnabled =
 		! blockType ||
 		hasBlockSupport( blockType, '__experimentalToolbar', true );

packages/block-editor/src/components/block-tools/style.scss

@@ -110,6 +110,12 @@
 		z-index: z-index(".block-editor-block-popover");
 		display: block;
 		width: 100%;
+		overflow: hidden;
+
+		.block-editor-block-toolbar {
+			overflow: auto;
+			overflow-y: hidden;
+		}
 
 		border: none;
 		border-bottom: $border-width solid $gray-200;
@@ -133,33 +139,47 @@
 
 	// on desktop and tablet viewports the toolbar is fixed
 	// on top of interface header
+	$toolbar-margin: $grid-unit-80 * 3 - 2 * $grid-unit + $grid-unit-05;
 	@include break-medium() {
 		&.is-fixed {
-
 			// leave room for block inserter, undo and redo, list view
-			margin-left: $grid-unit-80 * 3 - 2 * $grid-unit + $grid-unit-05;
+			margin-left: $toolbar-margin;
 			// position on top of interface header
 			position: fixed;
-			top: $admin-bar-height + $grid-unit - $border-width;
+			top: $admin-bar-height;
 			// Don't fill up when empty
 			min-height: initial;
 			// remove the border
 			border-bottom: none;
 			// has to be flex for collapse button to fit
 			display: flex;
 
+			// Mimic the height of the parent, vertically align center, and provide a max-height.
+			height: $header-height;
+			align-items: center;
+
 			&.is-collapsed {
 				width: initial;
 			}
 
+			&:empty {
+				width: initial;
+			}
+
 			.is-fullscreen-mode & {
 				// leave room for block inserter, undo and redo, list view
 				// and some margin left
 				margin-left: $grid-unit-80 * 4 - 2 * $grid-unit;
-				top: $grid-unit - $border-width;
+
+				top: 0;
+
 				&.is-collapsed {
 					width: initial;
 				}
+
+				&:empty {
+					width: initial;
+				}
 			}
 
 			& > .block-editor-block-toolbar {
@@ -245,7 +265,7 @@
 
 			.show-icon-labels & {
 
-				margin-left: $grid-unit-80 + 2 * $grid-unit; // inserter and margin ;
+				margin-left: $grid-unit-80 + 2 * $grid-unit; // inserter and margin
 
 				.is-fullscreen-mode & {
 					margin-left: $grid-unit * 18; // site hub, inserter and margin
@@ -318,7 +338,12 @@
 	// except for the inserter on the left
 	@include break-medium() {
 		&.is-fixed {
-			width: 100%;
+			width: calc(100% - #{$toolbar-margin});
+
+			.show-icon-labels & {
+				width: calc(100% + 40px - #{$toolbar-margin}); //there are no undo, redo and list view buttons
+			}
+
 		}
 	}
 
@@ -328,6 +353,9 @@
 	@include break-large() {
 		&.is-fixed {
 			width: auto;
+			.show-icon-labels & {
+				width: auto; //there are no undo, redo and list view buttons
+			}
 		}
 		.is-fullscreen-mode &.is-fixed {
 			// in full screen mode we need to account for