src/vs/base/browser/ui/menu/menu.ts/getMenuWidgetCSS
function getMenuWidgetCSS(style: IMenuStyles, isForShadowDom: boolean): string {
	let result = /* css */`
.monaco-menu {
	font-size: 13px;

}

${formatRule(Codicon.menuSelection)}
${formatRule(Codicon.menuSubmenu)}

.monaco-menu .monaco-action-bar {
	text-align: right;
	overflow: hidden;
	white-space: nowrap;
}

.monaco-menu .monaco-action-bar .actions-container {
	display: flex;
	margin: 0 auto;
	padding: 0;
	width: 100%;
	justify-content: flex-end;
}

.monaco-menu .monaco-action-bar.vertical .actions-container {
	display: inline-block;
}

.monaco-menu .monaco-action-bar.reverse .actions-container {
	flex-direction: row-reverse;
}

.monaco-menu .monaco-action-bar .action-item {
	cursor: pointer;
	display: inline-block;
	transition: transform 50ms ease;
	position: relative;  /* DO NOT REMOVE - this is the key to preventing the ghosting icon bug in Chrome 42 */
}

.monaco-menu .monaco-action-bar .action-item.disabled {
	cursor: default;
}

.monaco-menu .monaco-action-bar.animated .action-item.active {
	transform: scale(1.272019649, 1.272019649); /* 1.272019649 = √φ */
}

.monaco-menu .monaco-action-bar .action-item .icon,
.monaco-menu .monaco-action-bar .action-item .codicon {
	display: inline-block;
}

.monaco-menu .monaco-action-bar .action-item .codicon {
	display: flex;
	align-items: center;
}

.monaco-menu .monaco-action-bar .action-label {
	font-size: 11px;
	margin-right: 4px;
}

.monaco-menu .monaco-action-bar .action-item.disabled .action-label,
.monaco-menu .monaco-action-bar .action-item.disabled .action-label:hover {
	color: var(--vscode-disabledForeground);
}

/* Vertical actions */

.monaco-menu .monaco-action-bar.vertical {
	text-align: left;
}

.monaco-menu .monaco-action-bar.vertical .action-item {
	display: block;
}

.monaco-menu .monaco-action-bar.vertical .action-label.separator {
	display: block;
	border-bottom: 1px solid #bbb;
	padding-top: 1px;
	margin-left: .8em;
	margin-right: .8em;
}

.monaco-menu .secondary-actions .monaco-action-bar .action-label {
	margin-left: 6px;
}

/* Action Items */
.monaco-menu .monaco-action-bar .action-item.select-container {
	overflow: hidden; /* somehow the dropdown overflows its container, we prevent it here to not push */
	flex: 1;
	max-width: 170px;
	min-width: 60px;
	display: flex;
	align-items: center;
	justify-content: center;
	margin-right: 10px;
}

.monaco-menu .monaco-action-bar.vertical {
	margin-left: 0;
	overflow: visible;
}

.monaco-menu .monaco-action-bar.vertical .actions-container {
	display: block;
}

.monaco-menu .monaco-action-bar.vertical .action-item {
	padding: 0;
	transform: none;
	display: flex;
}

.monaco-menu .monaco-action-bar.vertical .action-item.active {
	transform: none;
}

.monaco-menu .monaco-action-bar.vertical .action-menu-item {
	flex: 1 1 auto;
	display: flex;
	height: 2em;
	align-items: center;
	position: relative;
}

.monaco-menu .monaco-action-bar.vertical .action-label {
	flex: 1 1 auto;
	text-decoration: none;
	padding: 0 1em;
	background: none;
	font-size: 12px;
	line-height: 1;
}

.monaco-menu .monaco-action-bar.vertical .keybinding,
.monaco-menu .monaco-action-bar.vertical .submenu-indicator {
	display: inline-block;
	flex: 2 1 auto;
	padding: 0 1em;
	text-align: right;
	font-size: 12px;
	line-height: 1;
}

.monaco-menu .monaco-action-bar.vertical .submenu-indicator {
	height: 100%;
}

.monaco-menu .monaco-action-bar.vertical .submenu-indicator.codicon {
	font-size: 16px !important;
	display: flex;
	align-items: center;
}

.monaco-menu .monaco-action-bar.vertical .submenu-indicator.codicon::before {
	margin-left: auto;
	margin-right: -20px;
}

.monaco-menu .monaco-action-bar.vertical .action-item.disabled .keybinding,
.monaco-menu .monaco-action-bar.vertical .action-item.disabled .submenu-indicator {
	opacity: 0.4;
}

.monaco-menu .monaco-action-bar.vertical .action-label:not(.separator) {
	display: inline-block;
	box-sizing: border-box;
	margin: 0;
}

.monaco-menu .monaco-action-bar.vertical .action-item {
	position: static;
	overflow: visible;
}

.monaco-menu .monaco-action-bar.vertical .action-item .monaco-submenu {
	position: absolute;
}

.monaco-menu .monaco-action-bar.vertical .action-label.separator {
	padding: 0.5em 0 0 0;
	margin-bottom: 0.5em;
	width: 100%;
	height: 0px !important;
	margin-left: .8em !important;
	margin-right: .8em !important;
}

.monaco-menu .monaco-action-bar.vertical .action-label.separator.text {
	padding: 0.7em 1em 0.1em 1em;
	font-weight: bold;
	opacity: 1;
}

.monaco-menu .monaco-action-bar.vertical .action-label:hover {
	color: inherit;
}

.monaco-menu .monaco-action-bar.vertical .menu-item-check {
	position: absolute;
	visibility: hidden;
	width: 1em;
	height: 100%;
}

.monaco-menu .monaco-action-bar.vertical .action-menu-item.checked .menu-item-check {
	visibility: visible;
	display: flex;
	align-items: center;
	justify-content: center;
}

/* Context Menu */

.context-view.monaco-menu-container {
	outline: 0;
	border: none;
	animation: fadeIn 0.083s linear;
	-webkit-app-region: no-drag;
}

.context-view.monaco-menu-container :focus,
.context-view.monaco-menu-container .monaco-action-bar.vertical:focus,
.context-view.monaco-menu-container .monaco-action-bar.vertical :focus {
	outline: 0;
}

.monaco-menu .monaco-action-bar.vertical .action-item {
	border: thin solid transparent; /* prevents jumping behaviour on hover or focus */
}


/* High Contrast Theming */
:host-context(.hc-black) .context-view.monaco-menu-container,
:host-context(.hc-light) .context-view.monaco-menu-container {
	box-shadow: none;
}

:host-context(.hc-black) .monaco-menu .monaco-action-bar.vertical .action-item.focused,
:host-context(.hc-light) .monaco-menu .monaco-action-bar.vertical .action-item.focused {
	background: none;
}

/* Vertical Action Bar Styles */

.monaco-menu .monaco-action-bar.vertical {
	padding: .5em 0;
}

.monaco-menu .monaco-action-bar.vertical .action-menu-item {
	height: 1.8em;
}

.monaco-menu .monaco-action-bar.vertical .action-label:not(.separator),
.monaco-menu .monaco-action-bar.vertical .keybinding {
	font-size: inherit;
	padding: 0 2em;
}

.monaco-menu .monaco-action-bar.vertical .menu-item-check {
	font-size: inherit;
	width: 2em;
}

.monaco-menu .monaco-action-bar.vertical .action-label.separator {
	font-size: inherit;
	padding: 0.2em 0 0 0;
	margin-bottom: 0.2em;
}

:host-context(.linux) .monaco-menu .monaco-action-bar.vertical .action-label.separator {
	margin-left: 0;
	margin-right: 0;
}

.monaco-menu .monaco-action-bar.vertical .submenu-indicator {
	font-size: 60%;
	padding: 0 1.8em;
}

:host-context(.linux) .monaco-menu .monaco-action-bar.vertical .submenu-indicator {
	height: 100%;
	mask-size: 10px 10px;
	-webkit-mask-size: 10px 10px;
}

.monaco-menu .action-item {
	cursor: default;
}`;

	if (isForShadowDom) {
		// Only define scrollbar styles when used inside shadow dom,
		// otherwise leave their styling to the global workbench styling.
		result += `
			/* Arrows */
			.monaco-scrollable-element > .scrollbar > .scra {
				cursor: pointer;
				font-size: 11px !important;
			}

			.monaco-scrollable-element > .visible {
				opacity: 1;

				/* Background rule added for IE9 - to allow clicks on dom node */
				background:rgba(0,0,0,0);

				transition: opacity 100ms linear;
			}
			.monaco-scrollable-element > .invisible {
				opacity: 0;
				pointer-events: none;
			}
			.monaco-scrollable-element > .invisible.fade {
				transition: opacity 800ms linear;
			}

			/* Scrollable Content Inset Shadow */
			.monaco-scrollable-element > .shadow {
				position: absolute;
				display: none;
			}
			.monaco-scrollable-element > .shadow.top {
				display: block;
				top: 0;
				left: 3px;
				height: 3px;
				width: 100%;
			}
			.monaco-scrollable-element > .shadow.left {
				display: block;
				top: 3px;
				left: 0;
				height: 100%;
				width: 3px;
			}
			.monaco-scrollable-element > .shadow.top-left-corner {
				display: block;
				top: 0;
				left: 0;
				height: 3px;
				width: 3px;
			}
		`;

		// Scrollbars
		const scrollbarShadowColor = style.scrollbarShadow;
		if (scrollbarShadowColor) {
			result += `
				.monaco-scrollable-element > .shadow.top {
					box-shadow: ${scrollbarShadowColor} 0 6px 6px -6px inset;
				}

				.monaco-scrollable-element > .shadow.left {
					box-shadow: ${scrollbarShadowColor} 6px 0 6px -6px inset;
				}

				.monaco-scrollable-element > .shadow.top.left {
					box-shadow: ${scrollbarShadowColor} 6px 6px 6px -6px inset;
				}
			`;
		}

		const scrollbarSliderBackgroundColor = style.scrollbarSliderBackground;
		if (scrollbarSliderBackgroundColor) {
			result += `
				.monaco-scrollable-element > .scrollbar > .slider {
					background: ${scrollbarSliderBackgroundColor};
				}
			`;
		}

		const scrollbarSliderHoverBackgroundColor = style.scrollbarSliderHoverBackground;
		if (scrollbarSliderHoverBackgroundColor) {
			result += `
				.monaco-scrollable-element > .scrollbar > .slider:hover {
					background: ${scrollbarSliderHoverBackgroundColor};
				}
			`;
		}

		const scrollbarSliderActiveBackgroundColor = style.scrollbarSliderActiveBackground;
		if (scrollbarSliderActiveBackgroundColor) {
			result += `
				.monaco-scrollable-element > .scrollbar > .slider.active {
					background: ${scrollbarSliderActiveBackgroundColor};
				}
			`;
		}
	}

	return result;
}