Fix light theme detection logic (check absence of dark class)

scratch/port_streak_clean.py

@@ -87,8 +87,8 @@ def port_html():
     setInterval(() => {
       let isLight = false;
       try {
-        isLight = window.parent.document.documentElement.classList.contains('light') || 
-                  window.parent.document.documentElement.getAttribute('data-theme') === 'light';
+        // In Tailwind next-themes class strategy, light mode is defined by the absence of the 'dark' class.
+        isLight = !window.parent.document.documentElement.classList.contains('dark');
       } catch (e) {
         const p = new URLSearchParams(window.location.search);
         isLight = p.get('theme') === 'light';