fix: use gray shades for 404 glitch effect

Replace magenta/cyan with subtle grays for a more muted aesthetic

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

layouts/404.html

@@ -22,13 +22,13 @@
   }
 
   .glitch::before {
-    color: #ff00ff;
+    color: #888;
     animation: glitch-1 2s infinite linear alternate-reverse;
     clip-path: polygon(0 0, 100% 0, 100% 35%, 0 35%);
   }
 
   .glitch::after {
-    color: #00ffff;
+    color: #555;
     animation: glitch-2 3s infinite linear alternate-reverse;
     clip-path: polygon(0 65%, 100% 65%, 100% 100%, 0 100%);
   }