Replace ASCII art banners with mobile-responsive headers

- Replace fixed-width ASCII banners with CSS-styled section headers
- Add responsive styling for mobile devices
- Update home page, event pages, header and footer layouts
- Improve mobile experience with scalable headers and gradient dividers

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

layouts/home.html

@@ -3,12 +3,8 @@
   <p class="prompt">{{ .Site.Params.description | default "Welcome to the underground tech scene." }}</p>
 </div>
 
-<div class="ascii-border">
-<pre>
-+==================================================================+
-|                         UPCOMING EVENTS                         |
-+==================================================================+
-</pre>
+<div class="section-header">
+  <h2>UPCOMING EVENTS</h2>
 </div>
 
 {{ $futureEvents := where .Site.RegularPages "Section" "events" }}