---
type: Layout Pattern
name: fixed-sidenav-shell
title: fixed-sidenav-shell
category: Viewport / Shell
description: Keep side navigation stable while main content scrolls.
primary_spatial_problem: Keep side navigation stable while main content scrolls.
secondary_spatial_problems: none
layout_axis: both
content_shape: mixed
responsiveness: fluid
constraints: Uses only local class hooks and explicit layout constraints.
scroll_ownership: Pattern owns the named scroll container.
source_lineage: https://carbondesignsystem.com/elements/2x-grid/overview/
lifecycle: generated
generated_from: scripts/generate-patterns.mjs, scripts/pattern-data.mjs
---
<!-- Generated from `scripts/generate-patterns.mjs` and `scripts/pattern-data.mjs`. Do not hand-edit generated catalog or pattern docs; edit the source files and regenerate. -->

# fixed-sidenav-shell

## When To Use

Use this pattern when you need to keep side navigation stable while main content scrolls.

## HTML

```html
<section class="fixed_sidenav_shell" aria-label="Settings">
    <nav class="fixed_sidenav_shell_list"><a href="#">Profile</a><a href="#">Billing</a></nav>
    <main class="fixed_sidenav_shell_main">Editable settings form scrolls independently</main>
</section>
```

## CSS

```css
.fixed_sidenav_shell {
    display: grid;
    grid-template-columns: 16rem minmax(0, 1fr);
    grid-template-rows: minmax(0, 1fr);
    max-block-size: 100dvh;
}

.fixed_sidenav_shell_list {
    min-block-size: 0;
}

.fixed_sidenav_shell_main {
    min-block-size: 0;
    overflow: auto;
}
```

## Core Properties

- `display`, `grid-template-columns`, `grid-template-rows`, `max-block-size`, `min-block-size`, `overflow` define the spatial behavior for this pattern.

## Properties That Break The Layout If Removed

- Removing `display`, `grid-template-columns`, `grid-template-rows`, `max-block-size`, `min-block-size`, `overflow` changes the pattern from its documented layout responsibility back toward ordinary flow or an unsafe fixed arrangement.

## Constraints And Change Points

- fluid responsiveness is part of the contract; change sizing values only when the new minimum, maximum, or wrap point is documented with the pattern.
- Keep the HTML class hooks and CSS selectors in one-to-one agreement.

## Scroll Ownership

Pattern owns the named scroll container.

## Accessibility And Source Order Notes

- Semantic role expectation: Preserve the HTML sample's landmark, list, navigation, form, figure, or article roles; layout classes must not replace semantic elements.
- DOM order expectation: Keep semantic elements, DOM order, reading order, and focus order independent from the visual placement created by the layout classes.
- Focus risk: Any interactive descendants follow DOM order; do not use this pattern to create a visual order that keyboard focus cannot follow.
- Scroll expectation: Pattern owns the named scroll container.
- Cognitive risk: Medium: scroll ownership can hide context, controls, or return points if it is not named in the consuming layout.

## Browser And Fallback Notes

The CSS uses modern grid, flex, intrinsic sizing, logical properties, or positioning. If a target browser cannot support a property, fall back to ordinary block flow before adding decorative or script-driven layout behavior.

## Composition Notes

Use `fixed_sidenav_shell` as the stable pattern root and compose additional layout behavior outside that root unless the child class is part of the documented relationship.

## Anti-patterns

- Do not add color, border, shadow, typography, or animation rules to reusable pattern CSS.
- Do not use this pattern to repair unclear HTML structure; make the DOM roles legible first.

## IA Navigation

Parent: [Viewport / Shell patterns](https://style.gallery/materials/v2/pages/patterns/viewport-shell/index.md) in [Pattern Categories](https://style.gallery/materials/v2/pages/patterns/index.md).
Next: [Layout Recipes](https://style.gallery/materials/v2/pages/recipes/index.md) for screen-level composition, or return to the [Layout Pattern Catalog](https://style.gallery/materials/v2/pages/CATALOG.md) when choosing another primitive.