[R-11] Global CTA button centering on mobile

[vmorps]

[R-11] Global CTA Button Centering on Mobile

Severity: P1
Sprint: 2
Component: All Sections
Spec: design/specs/responsive-layout-fixes.md § R-11

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Current Behavior

Several sections have CTA button containers that lack justify-content: center on mobile:

• Hero.module.css — .ctas (no centering) ��
• Standards.module.css — .ctas (no centering) ❌
• DeveloperFirst.module.css — .ctas (has centering ✓)
• ProblemSolution.module.css — .cta (has centering ✓)
• FinalCTA.module.css — .ctas (has centering ✓)

Expected Behavior

All CTA button groups across the landing page must be horizontally centered on mobile viewports. On desktop (≥ 1024px), section-specific alignment takes precedence (left for 2-column layouts, centered for full-width sections).

File(s) Impacted

• src/components/landing/Hero.module.css
• src/components/landing/Standards.module.css

Implementation Approach

For each affected component, add justify-content: center to the base .ctas rule. Override to flex-start at desktop where appropriate (Hero and Standards use 2-column grid layouts at 1024px+).

Acceptance Criteria

• All CTA button groups are centered on mobile across every landing section
• Desktop alignment matches the design intent per section
• Buttons wrap gracefully on very narrow viewports

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Branch strategy: All responsive fixes will land on a single branch (fix/responsive-layout) with one PR against main. Commits grouped by sprint.