Fix accessibility violations: color contrast, aside nesting

- Improve text contrast from #666/#888/#999 to #555/#6b6b6b across site (WCAG AA)
- Fix aside nesting in all 10 blog articles (aside→div in related-articles)
- Fix aside nesting in quote sidebar
- Update CRO enhancement CSS/JS inline colors

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

blog/articles/build-vs-buy-ai-automation-professional-services.php

@@ -64,14 +64,14 @@ include($_SERVER['DOCUMENT_ROOT'] . '/includes/nav.php');
             <p>There is a third option: building it yourself, using AI platforms and tools that make this accessible without deep technical expertise. For technically capable firms, this is worth considering for simple, low-stakes workflows. For anything involving client data, complex document types, or production-grade reliability requirements, the time investment in internal development typically exceeds the cost of commissioning a professional build — and the result is a system that needs ongoing technical maintenance rather than a delivered, tested solution with a warranty.</p>
 
         </div>
-            <aside class="related-articles">
+            <div class="related-articles">
                 <h2>Related Articles</h2>
                 <ul>
                     <li><a href="/blog/articles/what-is-an-ai-agent-professional-services">What Is an AI Agent? A Plain-English Guide</a></li>
                     <li><a href="/blog/articles/how-to-brief-ai-automation-consultant">How to Brief an AI Automation Consultant</a></li>
                     <li><a href="/blog/articles/cost-of-manual-data-work-professional-services">The Real Cost of Manual Data Work</a></li>
                 </ul>
-            </aside>
+            </div>
         <footer class="article-footer">
             <p>Written by <strong>UK AI Automation</strong> — <a href="/quote">Get a Quote</a></p>
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