Fix modal close buttons not working

CSS display:flex on .modal overrode the hidden attribute. Added
[hidden] { display: none !important } to ensure hidden always wins.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

public/styles.css

@@ -1,4 +1,5 @@
 * { box-sizing: border-box; margin: 0; padding: 0; }
+[hidden] { display: none !important; }
 
 :root {
   --bg: #fdf6e3;