Fix modern card background brightness in dark theme

Co-authored-by: brunoborges <129743+brunoborges@users.noreply.github.com>

Author: Copilot

site/styles.css

@@ -64,7 +64,7 @@ code, pre { font-family: 'JetBrains Mono', monospace; }
   --cyan: #22d3ee;
   --red-muted: #ef4444;
   --old-bg: #1a1412;
-  --modern-bg: #0f1419;
+  --modern-bg: #1a2838;
   --radius: 16px;
   --radius-sm: 10px;
   --nav-bg: rgba(11, 11, 15, .8);