2603.11 added dark/light mode

includes/theme_toggle.php

@@ -0,0 +1,16 @@
+<button class="theme-toggle" id="theme-toggle" title="Toggle theme" onclick="
+  var next = document.documentElement.getAttribute('data-theme') === 'light' ? 'dark' : 'light';
+  document.documentElement.setAttribute('data-theme', next);
+  localStorage.setItem('theme', next);
+  this.textContent = next === 'dark' ? '☀' : '☾';
+">☀</button>
+<script>
+  (function(){
+    var t = localStorage.getItem('theme') || 'dark';
+    document.documentElement.setAttribute('data-theme', t);
+    document.addEventListener('DOMContentLoaded', function(){
+      var btn = document.getElementById('theme-toggle');
+      if (btn) btn.textContent = t === 'dark' ? '☀' : '☾';
+    });
+  })();
+</script>