fix: darken text-secondary color for better readability (#97)

Author: xihale

assets/style.css

@@ -4,7 +4,7 @@
   --bg-primary: #ffffff;
   --bg-secondary: #f9fafb;
   --text-primary: #030712; /* Darker black */
-  --text-secondary: #374151; /* Darker gray */
+  --text-secondary: #111827; /* Much deeper gray */
   --text-tertiary: #6b7280;
 
   --border-subtle: #e5e7eb;