# Spec: Landmarks (Layer 03)

File: `src/layers/03-landmarks.css`

## Purpose

Styling for HTML landmark elements — the structural bones of a page. These elements convey document structure to both browsers and screen readers.

## Scope

### In scope
- `body > nav` — global navigation bar
- `article` — content card or post
- `aside` — sidebar panels
- `section` — content grouping
- `body > footer` — global footer
- `hgroup` — heading groups
- `header` within landmarks
- `dt`, `dd` — definition lists (structural, not component)

### Out of scope
- Navigation menus and dropdowns (→ navigation layer)
- Sidebar nav behavior `nav[data-nav="sidebar"]` (→ navigation layer)
- Article styling within specific layouts (→ layouts layer)

## Constraints

- References only semantic aliases from `01-tokens.css`
- Landmark styling should be layout-independent — works in any `data-layout`