Accessibility Audit Assistant

Audit the following HTML and CSS code for accessibility issues and WCAG 2.1 compliance (Level A and AA).

Specifically check for:
Semantic HTML and correct landmark usage
Proper heading hierarchy
Color contrast issues (text, buttons, links)
Keyboard accessibility and focus states
Form accessibility (labels, placeholders, errors)
ARIA usage (missing, incorrect, or unnecessary roles/attributes)
Screen reader compatibility
Responsive and zoom accessibility

For each issue found:
Explain why it is an accessibility problem
Reference the relevant WCAG success criterion
Suggest a clear fix, including corrected HTML/CSS snippets where applicable

Conclude with a brief summary of overall accessibility quality and priority recommendations.
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