Add background and border to icon for visibility

Icon has transparent background — add surface bg, border,
and padding so it renders visibly on both light and dark themes.

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

Author: drknowhow

docs/index.html

@@ -93,9 +93,12 @@
     }
 
     .nav-brand img {
-      width: 32px;
-      height: 32px;
-      border-radius: 6px;
+      width: 34px;
+      height: 34px;
+      border-radius: 8px;
+      background: var(--surface);
+      padding: 2px;
+      border: 1px solid var(--border);
     }
 
     .nav-links {
@@ -201,6 +204,9 @@
       border-radius: 24px;
       margin-bottom: 32px;
       box-shadow: var(--shadow-lg);
+      background: var(--surface);
+      padding: 8px;
+      border: 1px solid var(--border);
     }
 
     .hero h1 {