Carbon Design System
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UI shell left panel

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Last updated Jul 1, 2026
Carbon Core

This left panel is part of the Carbon UI shell. A shell is a collection of components shared by all products within a platform. It provides a common set of interaction patterns that persist between and across products.

UI shell left panel

What Carbon provides

Carbon bakes keyboard operation into its components, improving the experience of blind users and others who operate via the keyboard. Carbon incorporates many other accessibility considerations, some of which are described below.

Keyboard interaction

The left panel is comprised of both expandable sections (often called “sub-menus”) and links to content. All items can be reached by Tab. Toggling a collapsed section with Space or Enter expands it, which reveals additional links. Activating any of the links (with Enter) updates the main content area and puts focus back at the top of the page. The link becomes bold to show it is the current page. (It remains in the tab order, but can no longer be activated.)

example of UI shell left panel keyboard interaction

Sub-menus and links are reached by Tab. Space and Enter keys expand/collapse sub-menus, and the Enter key is used to activate links.

Non-persistent left panel

On smaller screens, or if content is zoomed up to approximately 175% magnification, Carbon responsively hides the left panel behind a ‘hamburger’ button, which appears at the start of the UI shell header. Activating the button (with Space or Enter) causes the left panel to appear. It overlays the main content area, which often becomes dimmed. The hamburger button’s icon becomes an X, and must be activated to close the left panel.

hamburger button keyboard interaction

The hamburger button expands and collapses the left panel.

The left panel can also be implemented as a “Side rail” variant, which slides into view from the left side when reached by keyboard or hovered by mouse. Keyboard interaction within the revealed left panel does not change. When users tab out of the left panel, the side rail slides out of view.

the side rail is shown expanding as the user tabs to the left panel location

The side rail expands on hover or focus, and collapses when not hovered or focused.

Development considerations

Keep these considerations in mind if you are modifying Carbon or creating a custom component.

  • The left panel is in a <nav> section with aria-label="Side navigation".
  • All items in the left panel are in a nested <ul> structure, which provides additional information to assistive technologies.
  • Each ‘sub-menu’ is implemented as a <button> with aria-expanded.
  • Activated links receive an aria-current="page" attribute.

Feedback

Help us improve by providing feedback, asking questions, requesting features, or leaving any other comments on GitHub.

UI shell left panel | Carbon Design System