mobile.fixed action obstruction

mobile.fixed-action-obstruction

Rule ID: mobile.fixed-action-obstruction Severity: WARN Category: mobile Target Standards: Apple Human Interface Guidelines (Bottom Toolbars & Screen Clearance), Google Material Design 3 (Bottom App Bars & Safe Content Boundaries), W3C CSS Positioned Layout Module Level 3 (Fixed Positioning)

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1. Overview & Core Invariant

Warns when fixed bottom elements lack compensating bottom padding on parent or content siblings, risking content obstruction

Core Invariant:

"Fixed bottom bars and floating action buttons must be accompanied by compensating bottom padding ('pb-16', 'pb-20', 'pb-24', 'pb-safe') on parent layouts or content siblings to prevent content obstruction."

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2. Technical Grounding & Engine Realities

Elements anchored with 'fixed bottom-0' float out of normal document flow, permanently covering the lower portion of the viewport.

Without compensating bottom padding (such as 'pb-24' or 'pb-[env(safe-area-inset-bottom)]') on the layout container or content siblings (

, , ), the final rows of text, interactive inputs, or submit buttons will be permanently hidden behind the fixed bar.

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3. Vulnerability & Risk Taxonomy

Risk Vector	Severity	Impact
Obstructed Content & Trapped Form Inputs	MEDIUM	The bottom-most form fields or submit controls are occluded by the fixed bar, blocking user progress.
Accidental Clicks on Fixed Bar	LOW	Users attempting to tap the bottom of the page accidentally trigger bottom navigation items instead.

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4. Non-Compliant Code Patterns (Bad Examples)

TSX (Fixed bottom nav without compensating bottom padding on main content):

<div className="min-h-screen bg-background">
  <main className="p-4 space-y-4">
    <p>Konten formulir paling bawah...</p>
  </main>
  <nav className="fixed bottom-0 inset-x-0 h-16 bg-card border-t">
    <button type="button">Beranda</button>
  </nav>
</div>

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5. Compliant Implementation Patterns (Good Examples)

TSX (Compensating bottom padding (pb-24) ensures full content clearance):

<div className="min-h-screen bg-background">
  <main className="p-4 space-y-4 pb-24">
    <p>Konten formulir paling bawah...</p>
  </main>
  <nav className="fixed bottom-0 inset-x-0 h-16 bg-card border-t pb-[env(safe-area-inset-bottom)]">
    <button type="button">Beranda</button>
  </nav>
</div>

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6. How to Suppress (Ignore Directives)

If this pattern is required for an intentional exception, suppress the diagnostic using the canonical Charites Rule ID:

<!-- charites:ignore mobile.fixed-action-obstruction intentional exception -->

// charites:ignore mobile.fixed-action-obstruction intentional exception

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7. Configuration Reference (charites.yaml)

rules:
  mobile.fixed-action-obstruction:
    severity: warn # error | warn | info | off

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8. Architectural Domain & Verification Reference

• Domain Architecture & Analysis Pipeline: See the mobile Category Guide.
• 1-SSOT Golden Tri-Corpus Test Matrix: See the Verification Harness on the Master Home page.
• Rule Catalog Index: See Master Wiki Home.