id: banner
label: Banner
family: family-e-feedback
category: Feedback
intent: Display persistent page-level messages
description: Banner message
composable: true
capabilities: OpenClose
required_parts: []
optional_parts: ["BannerContent", "BannerActions", "BannerClose"]
tags: ["banner", "announcement", "notification", "top", "message"]
keywords:
pain: Banner messages lack consistent visibility and accessibility behavior
promise: Visibility and ARIA behavior enforced by state and variant
why: |
BannerVariant controls semantic role and aria-live behavior. VisibilityState ensures correct open/hidden state without runtime logic. This guarantees accessible, consistent page-level messaging.
rules: ["CR-001", "CR-004"]
use_cases: ["system announcements", "warnings"]
related: ["toast", "alert", "callout", "inline_notice", "status_dot"]
file: banner_ui.css
tokens: banner-*, space-*, radius-*, font-*
foundation: spacing, radius, typography
states: ["open", "closed"]
island: banner_boundary.rs
pillar: feedback
badges: ["SSR Safe", "Hydration Safe", "Token Driven", "Deterministic API", "Zero Drift"]
before: |
// ❌ Typical
view! {
<div class="banner">"Maintenance scheduled"</div>
}
after: |
// ✅ CanonRS
view! {
<Banner>
<BannerContent>"Maintenance scheduled"</BannerContent>
</Banner>
}
boundary_type: init
block: []
blocks_primitives: [container, stack]